Last post on this, one on the tax thing, I think a few days ago there was a thread about how the people of Sicily were standing up to paying protection, so as far a street tax the writing is on the wall with that one...
As far as the black gangs go, there have been instances where the mob did business where there was Intersecting interest, Bumpy and the genovese, Barnes and Luchesses, lots of interaction in the Detroit mob, I think Vito had the Bloods with him in Canada, Joe Gallo, it's not like it's Never happened but generally, they don't intersect much noses it's the drug business...