This is the nightmare scenario for me. A forever subscription for the usage of a car.
Subscription for self driving will almost be a given with so many bad actors in tech nowadays, but never even being allowed to own the car is even worse.
If OSM is up to date - many places it is very outdated. (others it is very good).
Law - when a government changes the driving laws. Government can be federal (I have driven to both Canada and Mexico. Getting to Argentina is possible though I don't think it has ever been safe. Likewise it is possible to drive over the North Pole to Europe), state (or whatever the country calls their equivalent). When a city changes the law they put up signs, but if a state passes a law I'm expected to know even if I have never driven in that state before. Right turn on red laws are the only ones I can think of where states are different - but they are likely others.
Laws also cover new traffic control systems that may not have been in the original program. If the self driving system can't figure out the next one (think roundabout) then it needs to be updated.
I think this is purely psychological. The notion of paying for usage of some resource that you don't own is really rather mundane when you get down to it.