I'm tolerably certain y'all are putting way more thought into the setting than the author ever did.
I previously thought the same thing as you, and I believe I said so here, but then why make the endgame depend so heavily on all the stuff (age, species, legal status) that the series had previously ignored?
I mean, I’m used to Itou Hachi’s stuff focusing on the cute and letting the world-building slide, but stuff like the ID number/collar connection (and have any other beastkin ever been seen with a collar?) seems exceptionally (you’ll excuse the expression) random.
(Actually, checking Chapter 3, Marie has a little necklace and Fran wears a ribbon choker, but only Mel seems to wear bondage gear.)