Perhaps the above is the piece that should most be highlighted.
If the financial affairs are simple enough not to need probate and the deceased was doing everything online and you know the relevant access codes then … don’t tell the ATO etc. until after it doesn’t matter anymore.
That probably assumes that you can finalise everything inside a tax year but from the sounds of it that would apply for simple estates.
One thing to be careful of, particularly as we move towards, er, 1984, is that in order to continue to have online access to e.g. ATO and e.g. internet banking then you will also need to continue to have access to e.g. the deceased’s mobile phone.
So the order in which things are unwound needs to be very carefully planned.
I totally get what you are saying regarding the general problem … in such a stressful situation, the last thing you need is jumped up bureaucrats jerking you around, but unfortunately that is very likely to be the situation, at every step … and as @phb says the restrictions are at least well-motivated even if at times they are hamfisted in their implementation.
I don’t know how much your husband embraced technology but you might also want to review Apple's Activation Lock for another kind of potential problem.
