“Some small society that is ethnically homogeneous, has little drug use and high taxes so that no one can really get ahead or even has the ambition to kill anyone?”
I’m in the largest city in that country and it looks almost as ethnically diverse as New York.
“The lowest street crime ever was in Mafia-dominated parts of Manhattan and Brooklyn.”
You bring a proof from the Mafia??? Do you really think that that is the answer to the crime “problem”?
Did you know that New York City TODAY, with no Mafia to speak of, has the lowest rate of sexual assault of any city in the US that reports statistics, and also the lowest rate of property crime? I put “problem” in quotes because NYC has one of the lowest violent crime rates of any large city, too. Most of the homicides are related to illegal narcotics.
“They’ve clarified it pretty well; you’re mechuyav to kill a moser.”
Indeed they have clarified it. My rabbis say definitively that it is a chiyuv to report people to the authorities when they are a danger to the community. That includes people who commit sexual assaults (including on children), murderers, drug dealers, people who drive while drunk, ponzi scheme artists, and money launderers. I can’t see how anyone would rule otherwise. That would leave out people like illegal immigrants and those with minor zoning violations.
“I’m learning that Eid doesn’t mean only an Eid but any evidence that the crime has occurred.”
That is a serious pilpul on Rambam that is not consistent with the rest of the treatment of Noachide laws, where he simply follows the pshat of the gemara. Nowhere is there any suggestion that an eid is anything other than a witness. Remember that we are not talking about Jewish courts here.