These communities already have their own economies. I don't know how they do it now, but back in the 90s in San Fran I watched people pick up food stamps at a check cashing store walk out and within a block sell them to Vietnamese Mamasans (shop owner wives/mothers) for cash and then deliver cash to drug dealers. I also knew a tranny that could get cash off any credit debit card and fence stolen high end items from Union Square shops.

The efficiency and autonomy of the payments must be injected into the system in my opinion.