I grew up just outside of Boston.
The Mafia was better at keeping the peace than the police were. The Mafia didn’t like bad stuff to go down in their neighborhoods. People who did bad things in a mobster’s neighborhood would often disappear.
Those days are gone. It’s every man for himself, now.
The neighborhood would be the residence of the Mafia guys' families and friends. They wanted to keep their own loved ones safe. Plus being the protectors of the neighborhood would create good-will from the other residents, and a reluctance to cooperate with police.
I heard about the Mafia up there in New England too. It is sad when you have to depend upon criminals to protect you from criminals.
It is always every man for himself unless decent folks watch out for each other.
Reading this, and having grown up in a area where the most impressive estate around was "The Sicilian Club", the following explanation occurred to me.
The business of the Mafia was to make money providing contraband goods and illegal services to a larger society demanding both and willing to pay. Unshackled by legal niceties and equipped with a medieval willingness to inflict punishment on opponents anything which interfered with the conduct and profitability of that business was brutally and summarily dealt with.
The police, on the other hand, are low paid government functionaries more concerned with making it home to their families than anything else. And there's no blame or shame in that. But they lack the means and the motivation to do anything more than catalog the carnage around them, go home to their families, and collect their steady albeit meager pay.
Living in the home neighborhoods of the old time Mafia was akin to living within the walls of a robber baron's castle. As long as he wasn't robbing you, and assuming you didn't have the means to live in a Wayne Manor of your very own, it was one of the safest places where one could possibly reside.