As Captain Barbossa would say, "They're more like guidelines."
It turns out that the "best by" dates on food are no less arbitrary than the pirate code in a Disney film. Arbitrary is good for a laugh on the silver screen but bad for the amount of food waste we produce. As the Natural Resource Defense Council points out on its Switchboard blog, the expiration dates on food aren't governed by any regulation, so they are relatively meaningless.
The problem is that people are throwing away good food because those dates tell them it has expired. As a result, food is wasted, and so is the energy used to produce it. In addition, unless the food waste is composted, it becomes part of our trash.
Standards are needed to preserve the usefulness of expiration dates, and until we have that, saving good food comes down to our own judgment.