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.