What's Up With That?

Lately I keep seeing these "trik'd out" cars that have their license plates not in the normal place or position, but off to the side and diagonally placed on the back of the car. I am puzzled by this phenomenon. The only possible benefit I can think of for having this crooked placement is this...if you are a criminal and planning on fleeing the scene of whatever crime you choose to commit, it might make it more difficult for a witness to catch your license plate number....??? Why then is this not illegal??? Maybe it is, or maybe it soon will be when the legal system catches on to what I have already so keenly observed. I should have gone into law enforcement....