The cars will indeed refuel themselves. They'll be electric and if your Roomba can do it so can a robot car. They won't repair themselves but if your taxi driver repairs their car you probably should be looking for another taxi driver. (Why would a qualified mechanic be driving a taxi?) That just leaves the cleaning. A few low paid workers in a shed replacing hundreds of drivers is not exactly a massive financial burden. The first company to market with robot taxis will make a killing and one of the first corpses will be Uber.