What are those ranges (5-15%) based on? Do you have insider information regarding how much it costs Apple to run the app store (i.e., what their specific margins are for the app store and not broader company products and services)?
In 2019, Apple reported paying developers $35 billion, which means the app store had revenues of around $50 billion (this isn't exact though because many apps drop down to 15% commission after the first year). We can safely say Apple had at least $42 billion in revenue so the true range of app store sales is 42-50 billion). Apple therefore earned $7 - 15 billion.
If Apple charged only a 5% fee (which would be significantly lower than any other company in the world with a similar service), they would earn $2.1 - 2.5 billion. Does running that app store cost less than that? Do we allow any room for profit margins? Apple also doesn't receive money for truly free apps but they still provide a platform and general background support of them.
Let's go with 15% (which a number of subscription apps already receive). Apple receives $6.3 to 7.5 billion. Is that enough to run the app store? Maybe. Does it leave much margin? I don't know.
About 10 years ago it was estimated Apple ran the app store at just over break-even:
https://www.cnet.com/news/figuring-apples-app-store-gross-profit/
While it's unlikely (but possible) they are still doing that, none of us know how much it costs Apple to run the app store. Saying Apple "should" make the commissions lower is just guessing.
Here's a way to look at it and make a more realistic criticism of Apple's app store fees. This isn't valid but is more valid than just making blanket statements about what the fees should be. Apple has high margins on services (but not necessarily the app store specifically). However, they have company-wide net margins around 20%. This means, if we are going to make up numbers about how much commission Apple should receive, we can safely reduce the current fees by 20%. The new fees are 24% for the first year and 12% after that for ongoing subscriptions. Again, we don't know if Apple would be losing money at those rates because we don't know how much money Apple makes from the App store (we can guess general revenue but don't know profits).