If you're imagining that autopilot is anything more than driver assist technology, then there already is numerous malfunctions, autopilot fucks up regularly. With or without NHTSAs involvement, Autopilot (or Comma one) wasn't designed to be safety critical autonomous driving technology. NHTSA has about as much business regulating it as it does regulating whether or not you can hang dice on your rear view mirror.

If it were a form of birth control, level 2 would be the pull-out method: no guarantees, so be vigilant.

Nope. I'm imagining that NHSTA keeps people safe, and I don't want a car anywhere near me that's controlled by something that the NHSTA hasn't had a chance to even evaluate.

It's foolish to believe that real humans, driving real cars, will treat these technologies as mere "driver-assists." Autopilot is used -- shockingly enough -- as an autopilot. And even if they /were/ used perfectly, these systems are exerting physical control over the car -- something that the National Highway Traffic Safety Administration has a distinct interest in managing. The NHTSA would be grossly negligent if they did not attempt to regulate these devices.