Serious question - how, in your thinking, does a fee equate to a condition for an alt store? I admit I have not studied the text of the law as so many here have so if it does state that any platform fees are not allowed please point me to the text.
Being allowed to still secure the platform is allowed and that requires resources. Apple may enforce app signing on all deployed applications, for example. And, iOS is still proprietary platform and may require usage fees separate from App Store fees. The mechanism to date has been using the App Store to calculate the fees but I imagine that was more for simplicity’s sake than because it was a fee specific to the storefront.
Would it be permissible (or better in your thinking) for Apple to have a two-tiered platform license - distribute via App Store @ $99USD / year + fees vs distribute via alternate mechanisms @ $10,000,000 / year with no other fees?