It just says it is done in accordance with manufacturer’s recommended method and specifications. I suspect that while the level of accuracy won’t be down to mm/hr, the level of accuracy will be sufficient to prove one was doing the speed measured.
I also see that one can request the calibration certificates for the device in most jurisdictions.
Over the last 50 years it seems to me that those who stick with imperial units are clearly not numerate - they don’t do any calculations in the unit they quote and probably were those who did poorly at school. They may as well revert to cubits and pecks. If you actually use the units then the correct descriptors are used e.g. who calculates in funds, shillings and pence any more? USA scientists all switched to SI 50 years ago so their papers are understood by the international community - you can communicate with them, but as NASA found to its great cost when a space craft crashed into Mars, some diehards get the units mixed. Consumers would be better protected with laws and regulations that mandated SI for all things.
Here’s a couple of interesting videos relating to redefining the kilogram that have a good balance between scientific jargon and sock puppets.
I concur with your frustration. I was a fourth grader struggling with fractions when the metric system was introduced and quickly decided it was an easier and more logical way to measure the world. That was confirmed in Form 4 when Mr Beltrame plied us with the SI metric system of units as our introduction to Applied Science. My dad’s Peugot never saw an imperial bolt, nor did the subsequent Mazda.
Never underestimate the power of culture and national pride in this argument. In our case of course in Australia we have none of our own - we defer to the United States of America today who took over from Britain in the 60’s. Both hold pride in their differing imperial systems and will never accede to that world dominating French rubbish no matter how easy or logical it is.
I keep to the metric standards in all things I construct, but find in the building trade some imperial cannot be avoided. Tradition seems to have a more tenacious hold there, supported by cheap Chinese imports designed for the American market. It is also a world where a 1/2 of this or a 1/4 of that measured by eye works well enough. She’l be right mate, no need for that fiddly measuring thing. Once CAD gets into the picture though the metric system comes back, even if in the form of “decimal inches”. 
One area of engineering where the imperial system has a stranglehold is electronics. Component dimensions particularly of the older leaded kind are invariably built on a 0.1 inch grid. That comes about through the history of PCB’s having arisen primarily through American and post-war Japanese engineering. The Europeans did try and metricate it but it never came to dominate in the market.
So lets keep pushing back against the less logical and inconsistent imperial system’s traditions but work with it where we must.
There are still those amongst us who appear challenged by the decimal point. It can be as confusing as fractions and counting in 12’s? Reality is there are instances where we still need to accept or understand there are differences. Some everyday items still contain engineering that in imperial is a whole number or neat fraction, which needs to be represented in 5 digits as micrometers when converted!
Yes, an all SI world and single ISO standard would be wonderful.
Note
I was being enlightened when we went metric and decimal. My text books were a blend of SI and American imperial units! The rules of thumb and everyday trades all worked in imperial.
There are still remnants of those days all around us. I still need two sets of tools to cover metric and imperial dimensioned equipment. Some of which if made for the US market is still very much in the 1950’s.
Ford pattern wheel studs? Golf buggy wheel rims?
Automotive wheel rims 
thanks for sharing this info,
As another person said, that mix-up was on an unmanned mission, not the Shuttle.
I noticed a couple of Aussie fabric shops selling “by the yard” recently and wondered if it was legal. Could not find the info you linked to so thank you for posting.
Fishing rods can mix both imperial and metric . I recently purchased a Wilson Sure Catch rod which is Australian made , On the rod it is marked Length 10’ 6" ( 10 foot 6 inches ) cast weight 8-26 gms .
Was fishing with an English guy recently and netted his catch for him . It weighed in at 5.8 KG’s . He asked me to convert it to pounds ???. When I checked the carp fishing tournaments in Europe they seem to always measure the fish in pounds .???
He also had a look at my Suzuki GLX car and asked me “How many miles to the gallon did it give ?”
I said " No idea . Around 6.5 litres per 100 K "
I guess each to his own .
UK road speed signs are still in Miles per Hour. Fuel has caught up to be sold by the litre. Fuel consumption, well? Does it really matter? mpg! 
It seemed to matter to him
We recently had a visit from a long-time friend of my wife and her husband who is a Vietnam Veteran.
They were going to catch up with a group of veterans for a party in Townsville and he was going to dress up as a wounded soldier, and he had bought a pair of crutches from a charity store.
The aluminium crutches had the height adjustments marked in imperial units, not metric.
I don’t know when aluminium crutches were first used in Australia but I expect it was well after the metric system was adopted.
They may have been manufactured in the U.S of A .
I seem to recall that trucks delivering fuel to petrol stations have to measure their deliveries at a particular temperature and pressure.
On the other hand, this is the same kind of story as Einsteins Theories of Relativity. Sure, they’re more accurate than what Newton postulated about gravity - but even today most engineers and scientists can rely upon the earlier theory. It’s only when you’re dealing with enormous scales, tiny scales, or need incredible accuracy that Einstein’s ideas are useful. Things like designing microprocessors, radio telescopes and GPS satellites - or missions to Mars.
Nobody doing physical trading will rely upon the new definition of a kilogram.
I’d be very surprised!
On a slight tangent, a woman at work mentioned her husband’s age to me the other day and then that she was seven years younger than him. It didn’t take me long at all to convert his age to 111111, while she is 111000.
It’s just logical that we should eventually move to binary - just as computers go quantum.
Completely agree, take the UK as an example, it’s taken them 50 years to partially convert to SI. They decided to hang on to the traditional mile, feet, pound and pint. Use mpg for fuel vehicle economy, yet pump litres of fuel into their tanks. All confusing and unnecessary, science has no room for tradition, just hard facts. A global 21st century world needs accurate standards.
My old tool kit consisted of British Whitworth, SAE and Metric spinners and tools. Now metric has made the rest absolete, but some country’s still hang on to imperial.
Unless you are an enthusiast or collector of old motor vehicles other than Japanese makes.
Which metric standard is that?
There are variations between Asia, Japan, and Europe in things as simple as AF sizes for bolts. A single set of metric spammers is rarely enough. Between a Toyota from Japan, Same from Italy and Daedong from South Korea there is always at least one or two exceptions required in the tool box. Importantly Australian structural hex head bolts follow one standard or convention for AF sizing, that may not be the same as imported Asian product. One mm less AF for a common thread form is a significant cost saving.
Some Asian manufacturers export to the USA equipment with metric standard components. Many adapt and follow imperial convention.
Yes, it must be annoying for those born post metric.
For those of us who have lived most of our lives in a dual imperial + metric world, it is simply how it is. Even today if you own a battery electric golf cart, the wheel hubs typically follow a Ford USA IE SAE stud pattern based of 4” or approx 101.6mm. Does how that standard is measured really matter?
International aviation measures speeds in knots and altitude, rates of climb etc in feet.
The planet can’t agree to Left hand drive or Right hand drive for vehicles. Although in electronics, the heart of our connected future, imperial notions remain. SMD devices are measured in tenths of millimetres and also hundredths of inches. Pin spacing for JDEC standard packages remain tied to tenths of an inch or whole multiples/fractions of. EG 2.54mm, 1.27mm, 0.635mm or … It’s a single international standard, measured in either system to suit local practice.
Whether an item is measured in metric or imperial it remains the same item. The notion there is a penalty in many instances is perhaps a false one. Many high value items only come in one version. It makes no difference by which system of measurement it is produced. Perhaps some exaggerate the penalty.
It seems pointless suggesting one system is better than another or saying one is a winner and another a looser. Not while there are so many examples where there is a common international standard independent of the original system of measurement.
I WISH I could buy fabric by the yard. Quilting is done in inches, and fractions of inches. All of my quilting rulers (all purchased in Australia) are in inches. All the patterns are in inches… but I have to buy fabric by the metre. The calculating does my head in. Thankfully, there’s an app for that 
I’m a Gen Y, and beyond learning inches to quilt, and having an idea of what a foot is from the unmentioned sandwich shop, I have no conception of what yards, stones, miles etc are. My older relatives and clients speak in these terms with alarming frequency and I have no idea what they are talking about. They do seem more poetic though, I’ll grant that. 6 foot tall, dark and handsome does sound better than 1.82m ¯_(ツ)_/¯
