Essentially iOS is built from open software. It is a subset of Mach kernel and subset BSD derivation of unix which NeXT and Apple evolved with their combined proprietary API’s, open source contributions and this proprietary subset of an operating system named iOS.There's no legal standing here. The fact that Apple makes the hardware, develops the OS and developer tools and controls software distribution within that OS, and has 1st party apps and services that come bundled with the hardware is nothing new. All of these companies knew all of these facts when they decided to start developing apps for iOS.
iOS is not an open development platform, nor is it a monopoly or is Apple big enough to wield its power over any market it competes in to give it an unfair advantage.
By definition iOS has a monopoly on Apple idevices. Apple AppStore reflects open source philosophy of free software, as in free beer. AppStore charges $0.0 to host, distribute and test software that it releases for free download. BUT AppStore is not free as in free speech. You want to charge, offer subscriptions and in other ways make money using Apple brand, AppStore or any of its proprietary IP hardware AAPL demands compensation.
Apple is neither stifling competition for free beer nor is it an encroachment into free speech, free news or free software. It, AppStore and its policies are supporting the security, open market competition and product choice of a free market to exist in a constellation of products it sells. Along side the free market co-exists non-free: for sale, subscriber and per seat licensed software exclusives.
At issue is whether AAPL and Apple’s monopoly on iOS through its AppStore unjustly entitles Apple to profit from “each” occurrence “every” time an app sells, charges subscription or in other ways profits by using iOS. The conundrum is that 3rd party app developers are entrapped contractually in a monopoly within a natural monopoly. Third party developers have only Android and iOS through which to sell - both monopoly’s. There isnt a third vendor. Thus a natural monopoly.