> Garmin Autoland will take a plane which is otherwise working and is in the sky and put it back on the ground because the pilot has a problem...
Indeed. For reasonable values of "land" and "on the ground." It's better than a non-trained pilot, but it also relies heavily on the concept of "emergency" in aviation, in which everything else is put on hold and everyone else gets out of the way.
It has basically nothing to do with driving a car.
First, the sky is large - "Big Sky Theory" is the term for it, and it generally means that you can fly around however and wherever you want without hitting anyone. Yes, there are controlled airspace segments, various levels for flying around, but the reality is that if you just ignored all of that and flew a plane from A to B, you wouldn't hit anyone (almost always). It breaks down a bit around airports, and there have been the occasional "plane A not talking to anyone and plane B not talking to anyone colliding" events, but they are exceedingly rare.
Second, large airports are going to be (almost by definition) controlled airspace, with ground response crews. And there are common airbands for radio communication. The Garmin system relies on these things.
If you hit the "Oh Crap!" button, yes. It will control an otherwise operational plane down to landing at some airport (I believe it prefers controlled airspace and emergency services, though I don't know details), and it will clear the road in front of it by setting the appropriate emergency transponder code and broadcasting prerecorded messages on the appropriate frequency that basically amount to "Get out of my way, I'm coming in for a landing at this airport on this runway." Which, for an incapacitated pilot, is absolutely the right thing to do. I'm fairly sure it won't clear the active runway, though. That's a problem for the humans on the ground.
But - literally everyone else in the sky will get out of their way, and ATC will ensure that. If there's an A380 on approach and this system is triggered near the airport, if ATC needs the A380 to get out of the way, they'll tell them to go around and go hold somewhere until the Cirrus is dealt with.
It's really a very, very different class of problem than self driving cars.