Earlier quoted context omitted.
Of course it's arbitrary - the whole fee structure of the app store (stores, to be fair) is arbitrary. 5% could be more than enough for everyone, but no, it has to be 30%...
Just wait until you learn what % retail used to charge developers for promoting, distributing, and selling software. People quickly forget what a tremendous liberation the App Store created for developers. It's also not about the developers, the success of the App Store comes from Apple's users. They trust the App Store because they trust Apple's curation/privacy/security. That's what has caused this flood of softwar…
People buy way more on Amazon, and Amazon doesn't rob 30% of your sales.