Computer assist or override is dangerous
There can be only one driver.
Either the car AI, or the human.
There are too many scenarios where a controlled crash or exit of the roadway is preferrable to any other alternative; where deliberately accelerating into the vehicle in front of you prevents a worse crash from a truck or other condition approaching the side or the rear, or even above.
It' sone thing for a crash to occur from the autonomous car AI. It's another thing entirely if I have a crash solution and suddenly it's taken from my control by a limited computer system.