It's like if an university released an app for it's student body, they were forced to allow anybody to sign up to the university with Apple pay. And give Apple 30% of the tuition.
… that does not follow. Apple's definitions aren't based on whether a good is free. It's based on whether the service is delivered without real-world interaction by the user.
Tuition at a brick-and-mortar college? No cut.
On-demand video service with tutorials? They get a cut.