That's great...until the adult or person of authority fails to act nice. Then what does the child do? At what age does the child learn how, as an adult, to decide when to act nice, and when to stand up to abuse?
When is a child taught how to be nice, rather than to just act nice? If you know how to be nice, then you can recognize the same in other people. Ypu don't need to see a badge or a collar or someone's age, to know they are treating you nicely. You just compare your actions to their's, and if you act nice and they act nice...then you know for sure, they are nice. You don't need to go ask friends or strangers on the Internet, is behavior X respectful?