Apple is directly competing with Spotify with their Apple Music streaming service. Since Apple has complete control over the iPhone ecosystem, they can set the rules to harm other streaming service, or let their own service completely break the rules.
These anti-competitive rules aren't just about Company A relying on Company B to do business. It's about Company B also directly competing with Company A.
Also, the EU regulations cap the fees and set up identical rules for everyone (unlike Apple where its own services are left through without a second thought even though they don't necessarily operate to the code).
Isn't VISA somewhat similar to an ecosystem? It's not perfect (you can not switch over all apps when switching from/to Android), but you still need to change something on your side. Yes, exchanging a plastic card is easier than switching a phone, but it's not fundamentally a different paradigm.
> Also, the EU regulations cap the fees and set up identical rules for everyone
I agree that this is a good idea, but it's not a fundamental problem with Apple's payment structure.