Humans being idiots? I can't imagine that.

edit: In seriousness, Tesla has hit upon the fundamental problem: there can't be an intermediary step between fully human controlled, and fully automated when it comes to passenger cars. Basic autopilot works in planes because pilots have extensive training, and there is constant monitoring and communication between the pilots and various air traffic controls - Everyone knows, or can know (mostly) where everyone else is in their local sky area.

Neither of these things are true of cars. As a result any measures to "bridge the gap" between human and machine are going to fail. Leave emergency measures to the machine? Safer, but it will pull control when drivers "feel" they are still in control, and no one will use it. People will cry nanny state and robot apocalypse. Leave emergency measures to the driver? Increase in accidents, because any driver relying on Autopilot is probably focusing on something else. If you ask someone who is not focused on the road to suddenly take the wheel in an emergency decision, it's gonna be a bad time.

Full automation, or full human autonomy, is what I'm saying.