Isn’t Apple only seeking a cut of sales of digital goods? You can sell physical merchandise like a real book, but you can’t sell an ebook without cutting them in.

I thought surely you can buy ebooks on the Kindle app for iOS. But a quick search and you are right - nope, you cannot buy books on the Kindle app for iOS. The option just isn't there.

And you can't even present a link to purchase digital goods through a browser... You can open Mobile Safari and search Amazon for a Kindle book, but you can't use an Amazon app of any sort to do part of it.

Weird, considering the fact that the Bandcamp app lets you buy music digitally via PayPal. Am I missing some important difference between the two?

I just downloaded Bandcamp for iOS and under Digital Album I see "Not available for purchase on this device" along with links to purchase the physical vinyl or CD.

Hm, you’re right. I didn’t notice it but the album I tried it was “digital download + limited edition print”... mea culpa.

They must be paying Apple their percentage of the proceeds, unless they have an exception.

I'm not sure. I've found this in the App Store Review Guidelines:

>3.1.5 (a) Physical Goods and Services Outside of the App: If your app enables people to purchase goods or services that will be consumed outside of the app, you must use purchase methods other than in-app purchase to collect those payments, such as Apple Pay or traditional credit card entry.

But if this applies to Bandcamp, then it would equally apply to Amazon... So I don't know.

That part really blew my mind. I spent a good 20min trying to find out how to buy audiobooks on audible

That’s clearly different. Same question could be asked for any banking app.