Google advertises their self-driving car has never caused an accident, and I think it creates the false impression that a computer-controlled vehicle is somehow incapable of "human error." In the end, a computer's are only as good as its programming and the data the sensors are feeding it. In an unforeseen situation, the self-driving car only needs to stop, turn on its warning lights, and tell its occupants to get out and walk. A pilotless airplane doesn't have any easy fail-safe options. Drones or UAVs do crash more often than the public is aware of. Maybe there will be self-flying passenger airplanes some day, but I will be long gone or too old to care.