Hello,
I clarified the guidelines, as they were not updated following the last discussion on the topic.
The guidelines now mention that the “stamps and other papers serving as a proof for tax payment or for a control” are out of the scope of Numista (https://en.numista.com/help/scope-of-the-numista-catalogue-200.html).
I removed the 3 narcotics tax stamps from the catalogue.
I'm not sure whether we should remove the catalogue “Scott Specialized Catalogue of United States Stamps & Covers” though. @JLHare mentioned that the catalogue could useful for tokens such as N#99780, which are in the scope of Numista.