> no more traffic

How? There would be a huge increase in demand on the roads. You said it yourself, you’d have to build more roads.

Unless you meant, no more [suffering] traffic, since you could just take a nap.

The only way I see self driving to be a true win if it is so efficient that you can remove all the roads and they become part of the mass transit system.

I would demand personal vehicles to pay a premium (cost plus) as they take up more space per person and add to infrastructure maintenance cost