I'm pretty sure this person has not in fact seen people selling milk they get from EBT. Unless you get industrial amounts of milk from EBT, how would you even go about selling whatever amount you get?

I once encountered a gentleman who offered to buy my groceries with his EBT card in exchange for a smaller amount of cash. I declined since it didn't seem worth the hassle. It probably does happen but not in the "reselling groceries" way and not at scale.