In a plane you also have far more time to react once the autopilot disconnects for whatever reason, than the fraction of a second that a car gives you.

This is a misrepresentation of the dumpster fire that was the WMATA train situation. Yes, the fatal crash was the last straw, but the root problem was not the automation system but rather the complete lack of maintenance that led to its inability to work properly. Congress refusing to fund maintenance and then falling behind 10-15 years on it lead to all kinds of systems failing. The fatal fire in the blue line tunnel under the river occurred with a human at the controls, but we’re similarly not blaming that incident on the perils of human operation.

The difference is, they have traffic controllers and the train have their own dedicated rails, almost no obstructions and a train into train crash danger situation rarely arises. The planes have a lot of maneuvering space to all sides.

Car traffic and streets are more dense and often have humans crossing them without regards to laws, bicycles, motorbikes, road construction and bad weather.

Not saying one auto pilot system is better than the other, however, they operate in different environments.