Starting a new playthrough of Pokemon Black 2 and I was faced with what seemed like a throw away line... it's not a point that the game delves on, and I'm not sure if it's ever brought up again in the entire series.
But in that line is a realization: Field Research.
Bianca mentions that it's good that you're out there with the pokedex in order to update the habitat information.
Like, I know on the face of it the line exists to hand-wave why pokemons that previously didn't exist in the region, or lived in different parts of the region, now are where they are. But on a practical level, the more I thought about it the more sense it made.
Like, if pokemon living habitats are as volatile as implied, then it makes perfect sense why you'd constantly need to have people out in the field to update the information. Which in turn leads to why it makes perfect sense why the professors are exploiting cheap child/teen labor to get it done.