Why Apple don't restrict any super-apps?
Some so-called "super-apps" are designed around payment system and create their own app ecosystem inside the single app. That is primarily use case for Asian tech - WeChat, Alipay, Go-Pay, PayTM, PayPay Rappi and etc.
How they manage to compile Apple's rules?
Short answer: They don't
Longer answer: They don't but they are so important to users in those markets that they would not purchase iphones if they could not use those applications there
So does bank apps, there has to be some kind of exceptions.
Maybe because pay apps count as banking? It would be absurd to charge 30% on banking.