Why are the Censors allowed to view something that they consider to be improper for the rest?

Kevin Smith and Trey Parker make some interesting remarks in some of their DVD commentary regarding the MPAA (Motion Picture ociation of America) and their censoring practices. They're really in the position to pick and choose what is deemed appropriate at will, with little regard to what anybody else thinks. But, it's mostly about money. They censor things so that the investors can maintain a certain image. If the investors feel that the content could damage their reputation, then the company wont hesitate to eliminate what it sees fit. One of many reasons I will always prefer independent art.