As far as regulations go:
- Let Apple require that apps accept Apple Pay as one form of payment - Let Apple take whatever cut they want for Apple Pay - Let apps inform users about Apple's cut - Let apps inform users about alternative, cheaper, ways to pay.
How could anyone be against transparency?
Let all the folks that allegedly love the "convenience" of Apple Pay so much continue to pay an extra 30%.
There's nothing stopping apple requiring subscriptions to appear on a unified management interface.
My Spotify subscription, for example, was purchased on their website, which I got to via a browser on my desktop computer. Apple has had no involvement whatsoever in my relationship with Spotify other than as a provider of some of the platforms on which I run Spotify's apps to use my Spotify service.
If Apple were to tell Spotify that Spotify must provide a way to cancel my totally outside of Apple Spotify subscription from Apple's subscription managements interface as a condition of being allowed on the App store I can't see the EU allowing that.
If apple requires them to use an api to pass "basic techincal compliance" (they could just use a callback and let the app handle the rest) that would be very much in the spirit and the letter of the law.
Apple creates these either-or narratives that you either accept exactly what they want at their egregiously inflated price, or you will get the crappiest most inconvenient basically fraudulent alternative. As if nothing was possible in between.