[MenhirMike]

> Realistically, including avionics and medical devices where the software is restricted by regulation (in theory) and where the manufacturer is legally liable for failure of their device?

Yes, absolutely. The responsible party is the operator of said equipment, and if they tinker with it, it's up to them to be compliant with FAA/FDA/HHS/etc. regulations or face proper legal reprecussions.

> More specifically, the radio in an iPhone can almost certainly be made to operate outside of licensed/compliant limits by tweaking the software.

See above. We can already do that today with WiFi chipsets that can be made to use frequencies that are illegal in a certain country. It's on the operator to ensure compliance. Alternatively, device manufacturers are free to use components that only work in a certain frequency spectrum - but that wouldn't prevent an operator from using them in another country.

We already solved those problems long ago.