It doesn't need to be almost perfect. Waymo, for instance has remote human assistance when it gets stuck, and even a human in a normal car drive to the scene an

It doesn't need to be almost perfect. Waymo, for instance has remote human assistance when it gets stuck, and even a human in a normal car drive to the scene and to get it unstuck if it's really bad. There could well be a point where those humans plus the tech are cheaper than a traditional full-time-per-customer human taxi driver. You might say people don't want those delays but we tolerate delays in normal commuting. An unattended bag on a tube station stopping trains, a car accident blocking traffic, traffic jams blocking traffic, mechanical breakdowns, etc. As long as they're infrequent enough, it should be OK for riders.