This is very suspicious to me. We raised free range chickens, (in a small way) for a few years: we used organic rules as our standard - although we were unable to source organic grain at the time. The major rule was, from memory, that the birds were not to be killed prior to 10 weeks. We purchased day old meat birds from a hatchery (grown from fertilised eggs imported from the UK - I believe virtually all meat birds grown in Australia are sourced by the same method): raised them until they were a minimum of 10 weeks old, before taking them to a processor. By this stage, they could barely walk, because they were carrying so much weight on legs that were unable to support them (the breeding genetics want big breasts etc, not worried about spindly ‘pins’…). Most of our birds were between 2kg-3kg, bare weight - there was one (probably 3-4 weeks older) I distinctly remember being closer to 4kg, more the size of a turkey!
I realise this is a long story, but I am very aware of the size/weight of meat chickens for general sale: they are processed quite early in their lives (cuts down the feed costs) and so are relatively small. I think that the Coles “special breed” is exactly the same as all the other meat birds in Australia, but allowed to ‘free range’ AND allowed to live 1-2 weeks longer!
Which brings me to ‘free range’ for meat birds… my experience taught me that the birds are very agile, and enjoy free ranging in their early (2 to 4 weeks of life), they become physically unable to move very far once the weight starts piling on. They were never as active, and “chook like” though, as our laying birds.
Ethically, I still buy only free range chicken, because I dislike factory farming, and at least they get some sunlight in their lifetime… and they taste good (but not as good as the ones we grew!!).
PS Just checked the current standards -
[2019 V1 standards “5.2.20. Selection of genetics shall be such as to conform to the principles and aims of organic production.
This shall include preference for slower growing species for meat production and species that are able to perform their natural social and physical functions. As a guide, meat chicken species should be grown to a minimum age of 70 days.”]