Check it again mate, it has nothing, and I said NOTHING, to do with sicilian mafia. Saviano's Gomorra narrates stories about "camorra", a criminal organization based in Campania, Naples' region. Both are criminal organizations, but are radically different from their origins to their criminal methodologies.
As an italian I was about to point out the same thing. Thanks for your correction. The roms (see http://en.wikipedia.org/wiki/Romani_people) are spread through all Europe and are not a Neapolitan only phenomenon. Shame for NYT for not doing their homeworks.