> You buy a FED legal item such as a lighter and do cash back for the cannabis purchase. (I'm not based in the US.) I don't get it — aren't the point-of-sales

> You buy a FED legal item such as a lighter and do cash back for the cannabis purchase. (I'm not based in the US.) I don't get it — aren't the point-of-sales system and card processing machine separate? How does cash back make a difference when all the card company knows is how much you're spending at a particular store?