As an iPhone owner I buy the phone including its OS and of course the APIs are part of it. So I am allowed to use them. The only purpose of OS APIs are to allow access to the phone that now belongs to me. They are there to be used. Without the APIs I wouldn't have bought the phone. It is my f.....g phone and I have paid already for the API. How can someone besides Apple itself argue that I should pay again indirectly through software licences for the API a second time, or actually basically for each App!
If you don't see a difference between a personal license to use iOS on your device and a developer needing a separate license to use iOS commercially, I don't know what to say, and then yes, I am going to sound crazy to you.
It's like buying a DVD doesn't give you a license to have a movie night and charge people $5 dollars to come see the movie in your theater. Showing the movie commercially requires a different license. I mean you could say "how can someone argue that Disney says I have to pay again, I already bought the movie" all you want, but that's how it works.