Earlier quoted context omitted.
I'm not a pilot, but I have had flying lessons. Airplane autopilots are extremely simple. They can basically fly you in a straight line, at a fixed altitude. Tesla's autopilot is actually way more advanced than those found in airplanes.
A commercial airliner autopilot (the kind people think of when you say autopilot) can perform evasive maneuvers and land the plane.
The difficult part is decision-making in non-standard situations like Sully landing on the Hudson with his A320.