Not necessarily; I find it doubtful a person can stay alert and ready to take the wheel at a moment's notice after the car has minded its own business for however long.

Hence, either /you/ drive, or /the car/ drives. If the car doesn't understand what is going on, it should stop. (Humans really suck at monitoring boring, monotonous processes. We cannot expect people to do so in a self-driving car for hour after hour on the off chance something happens.)

> I find it doubtful a person can stay alert and ready to take the wheel at a moment's notice after the car has minded its own business for however long

I don't mean so people can navigate; I mean so people can complain to a city or district when a road is improperly marked.