Apple lets me use iOS without charging me? Did you lost your Software Licensing Agreement for iOS? https://www.apple.com/legal/sla/docs/iOS13_iPadOS13.pdf
I'm not reading all that just to find out it doesn't include anything about anyone being charged for iOS.
Show. Us. Your. Receipt.
I said users paid for iOS and I explained it very clearly. When you purchase a phone, software licensing is included. When you buy a mac, software licensing is included. When you buy a Surface Pro, software licensing is included. The fact that Apple didn't sell iOS separately doesn't mean I didn't pay for it.
You bought an iPhone and Apple generously provided the OS for free. This is not complicated.