Yes, I have seen how people struggle to drive at low speed and can only do start/stop, accelerating to a way too high speed only to slam on brakes, repeating endlessly.

But really, did you seriously read my post as meaning people literally can't go slower than 20 so just plough into whatever is in the way? I'm obviously talking about an open road situation. Hardly any human drivers go under 20 by choice.

What does an open road situation have to do with the incident situation?