Earlier quoted context omitted.
Selfdriving taxis solves much of the 98% unused car problem.
They also create problems in terms of extra journeys as a private car will go from A to B, whereas a taxi goes from C to A to B to C. It's quite amusing as people try to come up with more efficient use of cars and typically end up reinventing public transport (e.g. buses, trains etc).
The big thing they do is to make a huge number of parking spots obsolete!
There will also be far fewer cars doing the same transportation work.