This is the standard rate for food stamp fraud. Everybody knows it. And there are convenience stores in EVERY neighborhood which perform this "service".
Of course, it's just as easy to accomplish completely underground: someone hands a friend a few 20's, grabs their friend's food stamp card, and goes to Winn Dixie or Publix and spends twice as much as they handed their friend.
Laws preventing the practice are inherently unenforceable. It's exactly why you shouldn't have widespread government programs like this. Virtually everybody who has food stamps, at some point, has committed this "crime" with a friend in a pinch.
It's the kind of government program which allows so much blatant fraud, with virtually no way of enforcing the law, that fighting it in any meaningful way is simply not feasible.
And the WHOLE country knows exactly what is going on.