The penalty is for preventing Spotify and other music streaming services from informing users of payment options outside the Apple app store.
The European Commission’s decision was triggered by a complaint by the Swedish music streaming service over this restriction and Apple’s 30% fee.
The EU competition enforcer said Apple abused its dominant position in the market for a decade.
Margrethe Vestager said, Apple had done this by "restricting developers from informing consumers about alternative, cheaper music services available outside of the Apple ecosystem.
The comparison is pretty poor, and I’m afraid you are not familiar enough with the topic. If I make an application with a subscription service, it must be sold on the play/apple store to reach users. Google/apple get a 30% cut of any subscriptions I sell, meaning if I make $10, they get $3. Since iOS/Android own 99+% of the smartphone OS market, there is no other alternative. So you say, “I understand they’re processing and facilitating the payment, but 30% of my earnings is way too much! I can process my own payments and have people sign up on my own website. When people go to purchase a subscription, I’ll just redirect them to their browser to complete the transaction…”
That’s what Apple/Google are doing. It’s a monopoly.