Did you ever speak to anyone about it? If it bothered you that much you should have quietly gone to management and expressed your displeasure.
I'm not saying be a jerk but continually ignoring rule infractions is like ignoring a bully-none of the bad behavior will get fixed because no one is complaining. We're our own worst enemies. I've lost track of the number of people who let fairly major infractions slide because they "want to be a good neighbor". By NOT at least trying to curb the behavior you condone it.