

You’re right, and it’s the same reason 2d printers didn’t destroy the book publishing business. It only really makes sense to print things that are either highly situational one-offs for our own purposes or things that someone else created but that aren’t economically justifiable to physically distribute to us.
Commodity items like toys are made to a ridiculous level of cost and process optimization with large and highly sophisticated equipment and molds, which won’t pay for themselves until they’ve sold a hundred thousand toys or more. 3d printers are not competing with that at all. The goal is not to do the same things they already do at scale. The goal is to do the things they won’t and can’t do at scale, that would be cost-prohibitive to set up the process and molds for, that you don’t have time to set up a whole process for because you need it right now. That’s where 3d printing shines. Even companies are using it for rapid iteration because it would simply take too long to keep changing the setup on a traditional process. But it’s never going to replace or “beat” traditional manufacturing and distribution for most things that are done in bulk.
Bingo, the goal is not to actually trace 3d printed guns, it’s to add another piece of evidence they can slap onto the target of their investigation to improve the chance of getting a conviction. Whether the accused is actually guilty of anything is truly irrelevant to the intended purpose of these kind of things, they are in practice assumed guilty by the prosecution unless proven innocent. The point is simply to make a convincing case to a judge or jury.