> Do you really think citizens policing each other is a good way to enforce laws?

Irrelevant, because this isn't citizens policing each other. (Though, I will note in regard to your question that the alternative of having a distinct subculture separate from normal citizens that inevitably views themselves aligned against the citizenry policing the citizenry is far worse than citizens policing each other, but yet that's what we mostly do.)

> This is going to get ugly real fast. It creates division and disharmony in a community

Lawbreaking creates division and disharmony in a community.

> Read history.

I’ve read quite a bit of it; but I disagree with your implicit analysis, which attributes to a method of enforcement that most modern societies have chosen for some laws problems that stem not from that source but from the particular laws which certain repressive societies enforced using that and other methods.