If I'm poking along I always wave the faster carts by. Simple act of courtesy that is easy to do.
Every now and then I see Mr./Mrs./Ms. Unconscious who has several carts jammed up behind him/her. How easy it would be to pull over and let the faster carts go on there merry way.
But wait, maybe they were on the safety patrol in elementary school and they want to "set the pace for safety"
BB