I don’t think it’s a nothing law. Not only does it help with reducing waste, but also a food safety thing. “Best by” or “best is used by” or “expiry dates” are pretty clear: use the product before the date.

In my own case, we have a brand of bread that does “sell by”. There is not uniform standard on how many days after the date, the bread is safe to consume. Internet wisdom gives you a wide range.