Car rental companies are the most likely first bulk buyers of self-driving cars. They already buy, store, maintain, and clean large fleets of cars. They're all set up to handle the problems of a big fleet of cars used by many people. Uber doesn't have that infrastructure.

Car rental companies would like to have a car pick you up outside baggage claim and drive you away, rather than using a shuttle bus to get you to their car lot. Customers will like that, too. Even if the cars aren't self-driving on all roads, if they can get from rental car storage to the airport and onto the freeway, that's enough to justify the technology.