As long as it requires some humans to be available to "assist", I'm not sure anyone would sell or buy such a vehicle. Or rent in the "car rental" sense. Taxi service is what makes sense.

If I own the car, and I'm sending it to do errands for me while I work or sleep, seems like the cost of someone being available to "assist" it at short notice would be prohibitive. Unless it requires assistance once a month or so.