Within a few days, their bodies would mysteriously start appearing in the morgue. That was generally enough to leave the survivors rushing to get out of Dodge.
The local police would get a commendation from the district for sending the crime rate plummeting. That was nice, but not quite as nice as the candy, flowers, baked goods and money which would be anonymously dropped off at the police station. And nobody ever wondered why or inquired as to the whereabouts of the missing miscreants.
That’s okay until a cop decides he wants your wife, LOL.
We have such a prison industry here that probably wouldn’t like their supply of very cheap, locked-up laborers being offed by vigilante citizens.
Personally I certainly could go for this idea.