I think americans are going to get left behind in this technology. It's not just the crumbling infrastructure, it's the lack of public transport options. I expect there will be plenty of cities around the world that will be adopting self-driving car technology long before the US does.
Surely lack of mass transit would be a boon to self-driving cars. Public transportation makes owning a car — self-driving or otherwise — less necessary.
The people who use public transport are much more likely to be users of share drive services. The target people for this technology, at least at the beginning, aren't going to be suburban or rural people, but urban people, and especially people with constraints such as no garage's or associated services and infrastructure. Any walk around New York, Singapore, or London, will demonstrate this.
These people will already be using public transport. They won't want to own a car if they don't need to. They'll want the convenience of a car, without the inconvenience of parking it and owning it. As more people do it, the costs associated with doing alternate things will increase (except, probably, for public transport). As less infrastructure is available for cars that sit empty all day in car parks, that empty-car infrastructure will get more expensive. When some bright spark recognizes that the space now occupied by a car-park, in a high-density city environment, can be turned into multi-million-dollar apartments, with a small private fleet of self-driving cars for their residents, there aren't too many wealthy people that won't want to have that property and service. There will be billions to be made.
All of these reasons, and more (like the insurance thing I talked about), I think, will contribute to it overtaking traditional methods of driving quite quickly when it is introduced.
Also, self driving cars can follow eachother and communicate closely. A group of cars could be like a train going along the road. Thus, much less roadway space is needed and valuable real estate brought back into use.
