SDi + Food Stamps + rent/fuel assistance + eligibility for education assistance and other Government goodies (free cell phones/internet!) = Fat city for some people. Don't forget all the independent charities on top of that. Once you earn the moniker of "poor person" in a society that can't stand the thought of suffering you can be rather comfortable if you know the ropes.
Typically the above goodies are in addition to a family member working under the table or maybe dealing dope. Nobody is living on $800/month pal.