When their annual revenue is $368 billion and their net income is $95 billion (in 2021), a couple hundred million dollars doesn’t really move the needle.

App review, XCode, each app gets a certain amount of iCloud storage outside of what the user pays, bandwidth, etc.

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.