While I don't want safety critical decisions to be made by cloud services so that my provider can charge me a premium to unlock even safer decision making, I think that it's pretty reasonable to start with full autonomy only on preprepared stretches of road.

If that was the deal then you could have connectivity built into the road or road furniture and if the car detected a lack of connectivity it should come to a safe stop or revert to manual control.

It seems like we could benefit from a technological principle of Subsidiarity. https://en.wikipedia.org/wiki/Subsidiarity