I don't want to own a self-driving car. I want the self-driving equivalent of a taxi or Uber. Press a button on my phone, the closest one shows up, drives me where I want to go, and then hangs out nearby for the next person or goes back to the closest designated parking location.

These self-driving cars will be cheaper than even UberX/Lyft/whatever, as there is no driver to have to pay. They can be smaller than a cab, taking up much less parking room (they can park too close for their doors to open, and they don't need to including seating for a driver), which can actually be a fairly significant cost in the city, where convenient parking spaces can sell for as much as a house does elsewhere.