The whole thing is about respect and that is in short supply despite the amount of times the word is used. Clubs get tainted by the behaviour of fans far from the ground let alone getting on the metro although there is little that can be done away from the ground and even in it most tends to be reactive.
It’s in short supply everywhere mate and definitely within football grounds.
People wouldn’t call Utd fans Munichs in work or in the pub so why do it inside a ground?