Lol ... some of these comments are a hoot.
I just thought of another possibility I hadn't considered.
What do you do when you come upon a car, sitting still at a two-lane intersection even after the light has turned green? Well, in my teens, I would have blasted on by. I now know better ... there is probably a good reason that car is sitting there (ambulance coming, slow pedestrian, animal ... any number of things), and the best thing to do is proceed with caution.
So I think they might just be slowing down not because they are inspired, ashamed, or otherwise. Likely because they figure if I'm stopping, there must be a good reason ... as in someone is coming.
Epiphany: I'm probably pissing people off!
__________________
Proud parent of a happy inner child ...