In relation to the transportation-problem being discussed, autonomous vehicles are much better than normal privately owned cars because (in theory) they do not need any parking, at least not in premium inner city ground. They can just drive away and park somewhere where they aren't disturbing anyone, and come back when needed. Alternatively, if they are part of a car sharing service, the % of time the car is not being used and is therefore a wasted resource is going down. A normal car is only being used for what, 5-10% of the day? the rest of the time it is a completely wasted resource. If a car is not owned by an individual but by a group of consumers, a much smaller amount of cars is needed to satisfy transportation needs for the entire group.

Of course, even though they have these two advantages, they will still pollute(if not electric, and even so because they must transport more mass than say a scooter, and the electricity still needs to be generated at an external power plant) and create noise pollution and they also need to use traffic lanes and road-infrastructure.

I'm not very excited by autonomous cars, at least for short-trip personal transport, as I don't think they're solving the real problem which is to not need cars in the first place.

However it's far far easier for commercial companies to invest $billions in them than it is for governments to invest $billions in the infrastructure to make cars redundant. Look at the bitching and moaning that happens whenever a new train line is proposed.