Where did common courtesy go?

I was baffled at the last bike show that I went to. It is common knowledge that you don’t touch another guys bike but over and over I watched dudes go up to different motorcycles touch the paint, seat and even have the balls to sit on it, not knowing or caring who it belongs to. When did it become ok to cross this line? The very line created by the Grandfathers before us that would grab you off the bike, kick your ass and send you on your way. Is it time to resort to those measures again? Let me know your thoughts