Apple gets at least $99 per year plus device sales and usage data if it's an app. They also get to sell App Store ads to competing banks.
But the money they make on ads in the App Store has to pale in comparison to how much they get from Google
Now there must be more but $99 * 20 million is not nothing in annual revenue which is mostly profit.
A “registered developer” is not necessarily a “paying developer”, you can register as a developer to get documentation etc.
If you are working for a company creating an app, not all developers need to pay to publish an app. Also Mac developers don’t pay to distribute an app.
If you have a company with 100 iOS developers, you only need to pay for one account that has permission to submit an app.
If you are exclusively a Mac developer, you don’t have to pay anything unless you are submitting to the Mac App Store.
What the heck is a nothingburger?