Yes, you are right. But even if there were such rules (like blue flag in F1) they would not be respected by many. You know how many rammers and people who spoil other people's races there are recently.
So there's no use in thinking about it, is it?
But anyways, I admit that during these Nascar races, we, regulars, should have such the "unwritten" blue flag rule. What do you think about that people?