Everything Dana said is true. I was given "food stamps" after Katrina, because it was impossible to get money out of the banks, with them all being closed. It a plastic card that I could use only at the only grocery store that was open, Costco. It would not work for alcohol, tobacco, and most non-food items. people doing drugs are not interested in trading Cheerios for drugs. there is not much of an exchange market there.
Has it ever occurred to you that their are a lot of people that would pay $50 for a $100 debit card and buy groceries with it?