In one case they were trying to categorize the content based on inspecting the manifest, shall we call it. If you start making decisions based on non-authoritative information, my experience is that you very quickly forget that it's non-authoritative. That slippery slope is universal, rather than particular to any examples in this thread. If it can happen, it will happen.

If you decide things without checking with a higher authority, then you are the Confused Deputy, and that typically ends badly. It's not Barney's fault he keeps getting locked in the jail cell. It's Andy's.