There’s definitely merit to what you’re saying. If we assume that all of the 215 Matchprint cards TCA Gaming acquired in 2013 were printed as part of the same batch, that definitely works, but what if there were 2 separate print runs? What if 2 of the trainer cards with 4 copies were printed several years after the others? In an ideal world verifying them would be possible in the way you describe.
If that was a possibility that grading companies could verify their legitimacy, in reality however in 7 years the majority of these have not been sent in for grading. Those lucky enough to have been active in the community when TCA Gaming offered these for sale in 2013, 2014 and 2016 will likely own a few of these Matchprint cards, but a lot of people will only own one copy if they’re lucky enough to get their hands on the card they’re after. Are they going to go to the hassle of trying to verify that they’re legitimate? Are they going to know that a copy they paid up to 5 digits for was printed by some guy with a stack of Matchprint paper and a printer from the early 2000s?
Patterns and chemical compounds within the ink are going to be practically impossible to fake, but in terms of the ink colour itself, Pokémon cards are notorious for their colour differences, even on sets with a small release. Back in February last year I posted about 2 Munch Eevee cards I’d picked up which looked different: www.elitefourum.com/t/printing-colour-differences-with-the-scream-eevee-card/22635/1. @quuador has a great reply there which shows lots of other examples.