And they do! Phone contracts, electric bills, shipping fees. Everyone gets their cut when they deliver a service to the user. After I get Twitter from the App Store, the service is delivered. The App Store isn't doing anything other than providing free OTA updates which they could charge for if they want (not my fault they don't). Why should Twitter continue paying the App Store once the service is delivered? Would anyone pay FedEx every time they use an appliance shipped by FedEx, just because FedEx brought it to their house years ago? This is the same ask the App Store has whenever a developer wants to collect payment from users.

And you can't even collect the payments yourself, even if you wanted to. And you can't tell users why payments are more expensive (not even through email or any web pages reachable through the app - Hey got kicked out for this). AND AND - this is truly outrageous mafia-like behavior - you can't sell your services for less outside of the App Store. That's right, if your monthly photo backup service is $9.99/mo on the App Store, you have to sell it for $9.99 on your web site, even if you want to sell it for $6.99/mo. And if you do sell it for $6.99 in your app, you have to accept the fact that 30% of your profits are just pissed away even before taxes.

An entire subset of online businesses aren't even financially possible because the 30% Apple cut and forced pricing model would eat up profit margins that would be healthy otherwise. I would happily sell a service for $9.99 in app and $6.99 on web, and give the user a choice, but of course I can't, because the App Store is a racket.