Here’s a video made by someone more qualified than I talking about that system. Short summary, it’s an emergency system hooked up to a dead man’s switch.
Here’s another video that might be interesting that shows some of the work that goes into an autoland.
Here’s a video about an accident that led to modern crew procedures. “Who is actually flying the aircraft?”
The thing about autonomous systems is it’s dangerous to think of them as fully independent. Autopilot or a self driving car or a driverless train aren’t smart in the same way a human or a dog or a horse might be. They’re not really autonomous, they’re just unsupervised.