A major advantage is that most of them have not been identified, and those that are the U.S. authorities don't have as long a jacket on them because of them having originated in Europe. Once LE tags them then they have the same problem as the american born guys.
Keeping to themselves and being "insular" also helps them. But if US guys act the same, they achieve the same results
I knew one Sicilian, Charlie Murgie. He wasn't bashful about reminding Michael, Jo Jo or anyone else that he was the only Sicilian amongst them. Charlie was the son of a Sicilian Father that emigrated to the US as a member of The Black Hand.
Charlie was very insular to say the least.
