It’s more complicated than that. A 2D rectangle with certain graphics is entirely different than a single part of a gun which may really look like anything. Would you recognize a trigger sear if I showed you one?

And if 3DP gun designers get blocked, they just have to alter the design slightly. Vs counterfeit currency which always and forever must look the same. If the 3DP database detection is loosened to catch lookalikes, then you have false positives for the guy making a desk lamp whose part just kinda sorta looks like a trigger sear.

Also, I am not aware of any open source 2D printers built from the ground up, but 3DP got started that way. So bypassing this would be insanely easy.

It’s political theater.