Do you think pilots sleep while the passenger jet you're riding in is on 'autopilot'?
How autopilot actually works in airplanes is unimportant, the public perception and Tesla's intentionally ambiguous play with the word is what counts.
The perceived definition is far from the real definition.
People hear things like "planes can basically land themselves" which is sort-of-true, and they think the planes can actually land themselves when the reality is that the pilots need to set up ILS properly, make sure the engine thrust is at a reasonable level, do the proper communication with Air Traffic Control, and only then (maybe) can the plane land itself.
Note: I'm not actually a pilot, so my details on landing with ILS might be a bit off.
That's why a relatively simple mechanism can autopilot a plane, but the same mechanism will crash a car in an instant.
(for instance, I couldn't help but think the "sex" bill clinton was grilled about could not have led to pregnancy)