There will have to be some MAJOR infrastructure changes for autonomous cars to become mainstream. A few are....
1. Insurance companies. They make money by charging high premiums on higher risk drivers, will everyone with an autonomous car have the same rate? Or you'll have some switch to change from auto drive to manual? Sounds a bit dangerous to me to be switching back and forth from autonomous to manual. But insurance companies are a big lobby. They'll have to figure out how to charge insurance for autonomous cars. Can you legally even have to have insurance for what your car does if you leave it in auto drive?
2. CHP and traffic tickets create billions in revenue. Will autonomous cars be allowed to break traffic laws? All those tickets like running stop signs, illegal lane change without blinker, and most especially DUI's will be eliminated(a good thing). But this will cost local government revenue billions without petty traffic infractions.
3.Lawsuits. For every accident, a person can be sued civilly, and just default or go bankrupt but now accident survivors and relatives can sue auto companies, creating the possibility for massive fraud. Auto accident ambulance chasing attorneys must be just drooling at the idea of class action lawsuits for some glitch or breakdown of autonomous technology.
4. Mechanics. It will take a while for all mechanics to be able to learn and be able to repair this technology. There will have to be new certifications, etc. All machines break eventually.
There will have to be a complete infrastructure change to implement autonomous cars on a large scale. This may take a while.