The middle age Italians treat the mafia as a business, they keep violence to a minimum and want to operate in the shadows, street gangs want to be out in the open and use violence like it is a sport. You dont see mob guys shooting out because they"be disrespectin the set" by being on another gangs street. Can you see a Gambino and columbo soldier shooting it out because they were both in brooklyn. You dont see a lot of 60 year olg black gangsters because they kill each other off over stupid unnecissary shit.