I brought my kid to a pumpkin patch for Halloween last year and this lady told her kids to simply cut in line so they can go do some fun thing first. I thought to myself "crap, I can't say anything because you know what'll happen." My elderly father didn't have that inner voice and told the lady to get her kids to the back of the line. Well, as I expected, lady totally went bananas, whipped out her cellphone, shouting "you don't talk to my kids!" calling my old man a racist... everything under the sun.
We're expected to simply sit back, mind our own business, and ignore bad/destructive behavior. If you believe in the social contract you're out of line.