I've browsed reddit long enough to know that human drivers don't just stop in the middle of traffic for no reason, they will stop in the middle of a railroad intersection, block a highway exit, reverse from a highway exit, drive into a highway exit in the wrong direction, drive into another vehicle, reverse into another vehicle, and spew fume at pedestrians and bikers, all the time.

Or at least frequently enough to supply multiple subreddits dedicated to these people.

A lot of human drivers blasted through intersections with lights that were out.

There were indeed accidents, and so yes, human cars were in fact stopped in the middle of traffic.