It sounds like you think "a vehicle that works in a limited set of circumstances" qualifies as a car. As a mode of transport in some areas, I get why that would seem useful. Busses, trams and trains work like that. And subways! I use all those: they're great.
I imagine the GP thinks of cars as "can go almost anywhere with limited immediate infrastructure, even some way off-road". That's how I think of them. I can imagine "driverless cars that operate like 1-5 person taxis in urban areas that have specialised roadways" could show up. But to me, these are not "cars". They don't get me to a party in the woods; they don't let me park up illegally when I need to sleep; they probably don't let me rush an injured person or someone giving birth to prepared to deal with the legal consequences later.. etc.
These things will not be "cars"; they'll be non-mass-public-transit.