Because they own the IP and they get to decide the terms of how it’s licensed.
This is like a company taking open source software, saying they like the code the community has given them, and asking why they should continue having to respect the terms of the license after downloading the code. The availability of the software (or models) does not equal a free license to use as you please.
A license allowing 100K devices for free is very generous. The businesses selling more than 100K units of anything will be significant operations. It’s fair that they’re asked to contribute financially.