Basically, cars and trains have a simple autopilot rule: if things go south, brake, stop, wait for instructions.

Planes simply can’t be told to pull the handbrake and wait rescue. The airplane crew is a very well dressed rescue team.

(Drones don’t count as they won’t carry people, so you can apply the rule if things go south “soft crash in the place you took off from”, which is nice but it means strike a power cable on the way to the soft crash or land on a person head, and in fact, you’d hood let the drone take off place completely free for emergencies. Real life personal example: Dude sent his drone from a parking lot, and the drone came back for an emergency, I was parking in that spot, if I came a little earlier that drone would have landed on top of my car. Now imagine two airbus 380 emergency landing on the same runway at the same time. If you make it simple they gonna crash one in the other, if you make it more complex you increase the point of failure of the machine and autopilot… ultimately, the more you try to code different scenarios the more new scenarios you open in an infinite spiral. Then you are back to the old set brakes and wait, which a plane can’t do). Or you use a human pilot so multiple pilots on multiple planes can adapt and sort it out.