The things with the italians is that their organisation have a long history in europe and also outside of europe.
In the US and Canada, the italians, the jews and the irish started this crime orgnisation in the new world. They began as a small organization, but were doing criminal stuff, when the criminal justice ws not prepare for this type of organisation.
Also, the mass immigration of italians and irish in many american countries, made it easier for criminal groups to work inside of their community, without people going to the police.