This class of citizen-vs-citizen law enforcement should be outlawed entirely. The inevitable result is greater societal division and hostility. They create more problems than they solve.
Operant conditioning research has shown conclusively that punishment does not work for remediating undesirable behavior. Instead, it makes individuals defensive, evasive, and hostile toward the punisher. It is one thing to have punishment meted out by the State under code of law, and quite another to be targeted by members of the public.