Self-driving cars are probably going to cause serious problems for society which outweigh their benefits.

The problems they can create are largely related to civil rights and liberties.

The apparent business model for these things is to move from sales to service, which means:

1). The public's ability to get around will be permanently subject to the capricious whims of a corporation.

2). People's daily activities and movements will be captured in large data sets, over which they have no control.

One of the things that worries me about this, is that we already see the government using corporate actors to circumvent the civil rights of citizens. (E.g., asking telecoms to store data about their customer's calls so the government can rifle through it at will.) Imagine a world where they have access to high resolution data about citizen movement.

A suitably obsequious corporation could probably be convinced to deny people transportation too. Want to go downtown to participate in a protest? Sorry, the cars aren't going downtown tonight. In fact, we've decided that you are an undesirable, so we won't be allowing you in our cars any more. You don't get to object because this is a private company offering a service to you. They can withdraw service at any time.

Self-driving cars, while heralded as a life saving technology, are likely to create a situation where people are completely dependent on a system which extends to them no rights.