Credit card is probably a reasonable lookup most of the time. When (most) people open a tab, they'll have to hand one over briefly. While name collisions happe

Credit card is probably a reasonable lookup most of the time. When (most) people open a tab, they'll have to hand one over briefly. While name collisions happen, within a segment this specific, it's probably rare. If you were trying to do it across all Walmart stores, it would be a constant problem.