If this (from another comment) is true: "A quick google tells me Walmart has 11% of the us retail market and an estimated 18% of the grocery market, however again this is not a good indicator of their overall size of pos transactions, it does indicate that their numbers are likely better than 6%."

Then 18% of all SNAP sales seem incredibly reasonable given they make up 18% of the US grocery market.

Even without that stat, this has always struck me as a substanceless, emotional argument. If you have a program to give people money to go spend on groceries in grocery stores, then they're going to use that money to go spend money in grocery stores.

If you're super concerned there might be a margin on those products, then what's the alternative solution to whatever the stated goal of SNAP is?

I guess you could always scrap SNAP and create government farms and bakeries or something. That could never be less efficient or have any unforseen side effects...