Have to say I am with "Karen" on this one. Unless its an event, where people are partying on (within reason), any unnecessary noise is an infringement on other campers, whatever shelter they choose to use. Whatever time of day. Why can't people use headphones? Why do others have to "share" it?
Rule 1 applies here.
Does remind me of a tour of Zimbabwe in the 90's. Every campsite we went to the same Land-rover turned up with Tintin characters painted down the side and Beautiful South "I love you from the bottom of my pencil case" playing on repeat. Soon grew old.