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.