Good food for thought. I do not think we can assume self-driving cars will operate free of charge on the existing infrastructure. A number of authors are predicting a massive increase in traffic and road use with autonomous cars. I can see governments wanting to charge for vehicles that use roads continuously. In addition, people’s existence is more than just efficiency. Who doesn’t have a favorite tool; adjusted just for them. There is a simple pleasure in that. Or using a tool or item that was their Mom or Dads.