I have been using Apple devices for almost 20 years, and I have never been forced to pay a 30% tax on all activity on my phone. I can avoid it by buying directly from the seller's website, and also I just avoid buying software subscriptions in general, but especially from the App Store.
99% of the payment activity I do on my phone (buying retail goods, travel arrangements, paying invoices) has no additional cost.
You're correct. You've just paid it on every app store purchase, and every in app purchase. That's because Apple, despite trying, have failed to completely lock in the payment infrastructure.
They really want to though. Maybe consider that.
No? Apple charges a fee on every app sale. Where do you think the app makers pay that walled garden tax?