The world where Apple is just completely fine with Apple users paying $13 instead of $10 for a subscription if they do it through an app is an interesting one. Obviously this makes a lot of money for them but when you think about it they must think very little of their customers treating them with disrespect like this. This is how 'Tim Cook's Apple' should be remembered.
From Apple's perspective they say they are helping their customers with things like making subscriptions easy to cancel and Apple thinks that's genuinely worth 30%. The fact that Apple doesn't want their customers to know they are paying more is an interesting wrinkle though.
Now this is also a problem with Android (and it's the fault of the app developers), but Android make switching to a different account easy. Apple, doesn't. So, when you have 3-4 apple accounts and want to cancel subscriptions, it's a pita since you need to logout and login to whichever account has the subscription.
Now, you might think that's not a typical use case, but I can assure you that in South East Asia, a lot of iphone users have multiple accounts. One recurring thing about Apple products is that they are designed by people who are not internationally minded (see for example the fact that you can't change the currency when using apple pay in a website and recalculate the totals without stopping the entire flow, or the fact that dual sim in iphones is an after thought and badly designed)