If that 10-30% is the part that Apple would other wise charge for their service, and that 10-30% is given away to make customers happy, they they are getting that service for free.
Or, to satisfy
@boss.king, they are getting it for ($99/number HBO subscribers) which is a number distinct from free.
I’m a customer (One of the two parties traditionally involved in a purchase) and they keep their upcoming releases secret from me.
I think you’re trying to draw lines around special cases here specifically because it’s Apple.
There is no god given right to sell through the AppStore. People do it because they make money from it. If there was a way to make more money, they would.