Autopilot also does not control yaw...
Advanced autopilots do. Not the real single prop Cessna mounted ones, this I give you (they'd cost more than the plane
), but those in liners, especially the long haulers, MUST be able to control all three axis.
Regardless, to build a plane that would be able to do all on its own (push-back, taxi, take-off, climb, cruise, descent, landing, taxi, park
) would not be absolutely impossible even nowadays. Planes that could realistically fly themselves without needing a pilot are technically possible... fact is that there are several factors that keep the builders to buy those hypothetical monsters, one of them is the reliability of all those systems (statistically, the more a system is complex, the easier some problem or failure can happen to it
), the other is the simple argument that it's true that about the 50% of plane accidents happen because of human error... but would you fly on a plane that has no pilot? Even one accredited to be able to do all the flight on its own from pushback to park?
I would not.
There is no such a thing as overkill. Only unworthy targets.