It's about the money flow. If the money flows from the User to the Developer, Apple wants a cut as a middleman.
The argument is that the store owner brought the customer to the seller, so they should get a cut - and it shouldn't be possible for the seller to avoid that cut by selling direct.
Ads have money flowing from the Advertiser -> Developer. Apple isn't involved in that relationship, and didn't bring the customer (the Advertiser) to the seller.
> The argument is that the store owner brought the customer to the seller
One problem is that Apple does not allow developers to bring customers directly. You always have to go through the Apple Store to install an app on iOS. So, even if you bring your own customers, you have to bring them through the iOS Store.
That may be the argument, but the result is that managing the free apps by companies like Facebook and Google in the App Store are subsidized by taking that 30% from tiny outfits like OmniGroup and Panic, that make paid productivity apps.
Responding to many of the arguments I read around on Twitter: I don’t see how anyone can use the word “fair” to describe this arrangement, no matter how many ways people compare it to a console like Nintendo.
The argument is that the store owner brought the customer to the seller, so they should get a cut - and it shouldn't be possible for the seller to avoid that cut by selling direct.
Ads have money flowing from the Advertiser -> Developer. Apple isn't involved in that relationship, and didn't bring the customer (the Advertiser) to the seller.