Arbitrary Apple rules. Apple decided that "physical" goods & services in app purchases don't get taxed (e.g., clothes, uber rides). Digital goods do because they feel like they can get away with it which is why you can't buy eBooks from Kobo or Amazon on iOS, can't buy or rent movies from Google on iOS. People will tell you this is for "safety" and to keep you from getting scammed but there's nothing stopping malicious actors from creating apps that promise to ship physical goods and just don't. At least with digital goods you should get whatever you pay for immediately after purchase.

Whether Apple believes it can strongarm the related companies.

I do wonder if a workaround here is buying a physical postcard from a patreon creator that comes with a free monthly subscription. A 50c mailed card would be cheaper for any subscription above $2.

That's the reason why Kindle doesn't sell ebooks on iOS

In many cases, it isn’t even a “purchase“ in any reasonable sense of the word - it’s a donation. Supporters don’t get anything other than knowing they’re helping a creator keep making something they like. This is akin to Apple wanting a 30% cut when you send your buddy $5 through Apple Pay. With this, Apple isn’t just interfering in business relationships, they’re interfering in personal relationships.

I’ve been pretty sympathetic to Apple in their tangles with the EU - I want my phone to be a locked-down appliance. But this is too far- it’s clear that Apple both has a lot of power and is abusing it.

The line is "can you use the purchase solely in the app distributed through Apple's infrastructure". I think their fee is outrageous, but that does seem like a defensible line.

Whatever you get as a Patreon patron isn't typically a physical product, unlike something you buy on Amazon (generally speaking) or a physical car ride. It's closer to a Netflix or a newspaper subscription, and Apple wants 30% of those too.

The line is wherever Phil Schiller fucking says it is.

Subscriptions I expect....