Amazon has taken down some listings. A spokesperson also told CNBC that vendors have to honor both the law and Amazon policies, including a guarantee that any item has a shelf life of at least 90 days. The company added that it uses a mix of human reviews and AI to study feedback, helping it flag products or whole seller accounts if it catches violations.

Expired food still appears to slip through the cracks, however, and Amazon's approach to third parties may be partly to blame. In addition to the confusion over who's selling, Amazon will cancel reviews if they're for orders it fulfilled using its warehouses -- while this is meant to "take responsibility" for the experience, it can also mask recurring problems. There are calls for better freshness guarantees and greater accountability when things go wrong, and it's not clear those will be addressed in the near future.