There should be a difference between a 30% cut of an app (of which apple can say their toolkits and os development are part of the product offering) and a 30% cut of a subscription, especially a multiplatform subscription. if you could buy netflix with applepay, but then 90% of your netflix usage is not on apple devices, apple collects on that entire subscription.

Subscriptions should be priced more like a credit card transaction fee. They could have marginal brackets that increase slightly at scales, to account for bigger apps possibly causing more backed development work.