I used public transit, taxis and car sharing services exclusively until I started a family. At which point setting up the carseat every time became prohibitively cumbersome and I bought my own car. Children's car seats are very personal in terms of size and configuration and are required by law.

I think things like that will make people want their own self driving car. You want the one that fits your wife and two kids and your dog. Or you're rich and you want to be driven around in a really nice one that hasn't been used by other people.

The more I think about it, the more I imagine rich people increasing their car ownership due to self driving cars. Take your fleet with you to the cottage or across the country, why not?