The safe disengage problem is solvable to match human level outcomes. Unexpected event? Slow down, avoid obstacles, flashing lights, slowly go to a spot that's ok-ish for parking.

Yes there can be a big hole in the road anytime, the AI has to watch the vehicle in front of it, if no such vehicle then it should chose a speed that let's it evaluate road conditions for the given weather/visibility.

Vehicle coming into our lane? The AI has to match human level maneuvering to evade the incoming car. It already has much better chance given it won't panic, will be always fully alert, and will be as accurate and precise as it can.

So the big categories are sudden road/environment changes (tree falls on road, hail, mudslide, earthquake damages road, animal crosses road), other vehicles, and pedestrians/cyclists/etc.

All are manageable with inferences from the environment (weather and roadside context determine visibility and how much space there is for maneuvering, how likely are unexpected crossings - eg. deer, kids) and surrounding traffic.

Are these hard? Sure, but none require human level cognitive reasoning.