I see people all the time at certain grocery stores offering to buy my groceries in exchange for cash (say $100 in groceries for $50 cash).
IN THEORY, this could stop some fraud by just giving people the food (canned veggies, canned fruit, etc.) rather than providing them the opportunity to do things they shouldn't.
In practice, this could turn out really bad. It could result in people getting LESS food. Plus, I highly doubt that Jesus would approve of poor people helping to pay for rich people's tax cuts.
Also, the canned food that they'll be given probably won't be the healthiest food ever.
Gonna cause more crime than anything else. Some people won't take that shit, and will rob before they take a box of food.