The whole point of mentioning taxis was that the part about self-driving cars where you don't have to control the vehicle and where the vehicle just goes and picks someone else up after you are done with it is already served by taxis. It's definitely likely that self-driving cars will displace taxis, but it's not clear that it will actually be all that cost-effective in most places. The argument to be made is that the driver is such a large fraction of the cost of a taxi that reducing that to a single fixed-cost addition of a computer + sensors is going to dramatically change the pricing structure in such a way that people will give up personal vehicles.

I think that's very likely not true in most places where population densities are low. There will probably be some rebalancing, but I don't think it will be as dramatic a shift as the parent comment made it out to be.