I think any automated vehicle, no matter how advanced, should always have a big red button to make it stop whatever it's doing. Kind of like the emergency brake on a passenger train.
If you hit the big red button going 65mph on the center lane of a crowded highway, it could be bad. Especially if the tech starts to feel safe enough that cars can travel close enough to use the draft from cars ahead.
I think an emergency brake works for trains because they’re isolated.