Where I live the rule is simple, and all stores adopted it. If something is mislabeled you get (one of) free, and all the rest at the lower price. (And you see

Where I live the rule is simple, and all stores adopted it. If something is mislabeled you get (one of) free, and all the rest at the lower price. (And you see a worker skurry off to fix it immediately.) And here's a shock, mislabelling is vanishingly rare... seems it can be done if desired...