USDA research done during the George W. Bush years showed that food stamp users allowed to get any grocery item included a smaller, not larger proportion of salted snack and soft drink products in their food orders. You are “fighting as though beating the air” as the bible puts it. Even bums on a budget are frugal, it turns out, and the overhead to do what you say you desire would be large.
I have to disagree, HTR. All of the items are electronically scanned in almost every location in the country. The card is also electronic. Any attempt at scanning an unacceptable item would automatically kick it out. Besides, it doesn’t seem to be hard for folks to reject a cigarette purchase made on the card, so I see no big deal even if it’s done by the cashier.
That process would not be hard or costly. And the study you cite simply says some are frugal. Those who aren’t are still a sizeable number, and if there’s any way to plant the idea that good things happen when people use their own money, then that is a neat lesson to teach.