An accident where it failed to listen to the driver overriding it and did the bad thing anyways, would be an unambiguous case. A trend where it was frequently

An accident where it failed to listen to the driver overriding it and did the bad thing anyways, would be an unambiguous case. A trend where it was frequently (over the background human accident rate) making decisions that resulted in it switching from driving normally to an accident being inevitable in less time than a human can react. Something like it frequently sharply turning the wheels at highway speed. Short of something like that which takes agency away from the driver, the driver is in control and responsible for the vehicle, whether they are using assistive technology or not. Accidents also happen already, it doesn't make sense to insist on assistive technology being superhuman at avoiding them.