I can imagine that if we went to 100% automated car travel, that punk kids and hardened criminals alike would be spending lots of time and effort trying to find new ways to make the system fail and cause massive car crashes.
I watch Top Gear (UK) and have noticed that in some countries it's not uncommon to drive your car onto a train, and let the train take many cars between cities, under the English Channel, etc. In America we still have a lot of railroad rights-of-way that could be refurbished or put back into service as intermodal passenger transport for things like daily commutes, inter-city trips and so forth.
Self-driving technology could be used to automate the loading and unloading of cars to speed up the process and make it safer. It could also be used to assist drivers who have had too much to drink. Not a ride home, but enough to get the car off the train.