A significant advantage aircraft on autopilot have is that the majority of the aircraft routinely using autopilot are flying under Instrument Flight Rules [IFR] and can rely on Air Traffic Control to provide separation from other aircraft.

Because of this, an aircraft under autopilot (especially one ascending and descending on its own) doesn't need to worry about hitting things. There is usually a distance of 3-5 miles¹ between the aircraft and other hard objects.

I would say calling the Tesla system an Autopilot is vastly understating its abilities.

¹ http://aviation.stackexchange.com/questions/2806/how-much-is...