To me it has nothing to do with the law, it is completely how rude and a rush people are in nowadays.
Example: Tuesday night I was in the return line at a local Walmart, I bought the wrong size pull-ups. Well the guy in front of my was rude, there was an issue with an item the person ahead of him was returning and the manager had to be called over and then a price check and so on and so forth. It did take long, like 15 minutes to return a DVD. Wel this guy ahead of me spoke rather loud "how many walmart workers does it take to return something" there were three there, I ignored him. Then he looks at me and says loud again so everyone could hear him "You would think they would open up another cashier because the line is SOOOOO long." I simple replied well that is not up to us we are not working here. I was not going to let his negativity get to me. The he said "WE all think you should open up another lane because you guys can not figure that out." I then said loudly "speak for yourself but DO NOT speak for me, I am fine waiting and there is no reason to talk rudely to someone even if you think it is taking longer then you think it should. The lady behind me said "I agree with you ms, Americans are just too much in a rush." The man was very unhappy with me, almost thought he was going to hit me, but I am sorry but being rude is not ok with me. Those workers where just trying to figure it out and do it correctly.
I live in Wisconsin and usually people obey the rule of moving over or letting the procession go through. Of course it really depends where you are driving, I have seen downtown processions broken up by rude drivers.