I don't think that's true. Almost none of the many variations of "sell by" or "best by" are required or regulated by the FDA -- they are entirely at the discretion of the manufacturer. The only one that is, is "expires on", and that's rarely on anything other than baby formula and baby food.
I can tell you factually, that here in California if I had expired product in use, or not in process of being thrown out and the Health Dept. showed up, I would have been written up and subject to fines if I did not rectify immediately. And of course all the grocery stores either throw out food past it’s sell by/use by dates or the more charitable donate to food banks when product is close to the date because it’s good customer relations.