Having rules in a sporting event doesn't mean that people won't break them. It just means that if they get caught they pay the consequences.
Sounds reasonable. That covers both laws (explicit) and cultural norms (understood) that affect conduct and provide potential consequences for said conduct. That would cover most of my examples and a whole lot more. As I said, the main difference between sport and "street" is that in sport the rules are more likely to be known to all parties, symmetric, and consistently enforced.
For anyone who insists that "there are no rules in a real fight," I offer this scenario:
You're an umpire for a Little League game. One day you make a call that a player's parent disagrees with and the guy comes up to you, screaming, insulting you, maybe even shoving you. He's clearly looking for a fight, so you grab his neck, pull him into a few hard knee strikes, throw him as hard as you can, then mount him and start raining down punches until you are pulled off.
When you are hauled into court for criminal charges (and the inevitable civil case - did I mention that this guy was a successful businessman before you inflicted permanent disability on him) you proudly tell the judge "It was a fight. There are no rules in a real fight."
Exactly how well do you think that will go over? Think you'll avoid going to jail and having your saving account emptied?
Bear in mind that everything you did would have been perfectly acceptable in the UFC. Surely it can't be the case that "real life" could have rules
more restrictive than sport competition?