Why wouldn't Uber just switch from being a marketplace bringing together riders and drivers, to a marketplace bringing together riders and autonomous cars (and

Why wouldn't Uber just switch from being a marketplace bringing together riders and drivers, to a marketplace bringing together riders and autonomous cars (and their owners)? I suppose a well-financed rival could buy huge fleets of vehicles and compete directly with Uber, but Uber doesn't have to make that capital commitment. They just continue to be the middle-man between the riders and the cars, except the cars are no longer managed by their drivers, but by their owners (whoever they might be, individuals or large corporations). Uber's big advantage is that they've already created the market. This is Paul Graham's idea about not automating in the early days of a startup taken to the extreme.