I don't disagree with you here. iOS and Android definitely constitute a duopoly worldwide, and Apple's market share in the US may be high enough for anti-trust

I don't disagree with you here. iOS and Android definitely constitute a duopoly worldwide, and Apple's market share in the US may be high enough for anti-trust concerns to apply. The key point is the percentage market share is an important consideration in determining whether a company has a monopoly or not. I'm only taking exception with claim that "Apple has a monopoly on iOS app stores" based on reasoning that ignores market share, because that reasoning is tautological. Also, Telegram's complaint was filed in the EU where Apple only has 25% market share and likely would not be considered to have a monopoly. > Before we think "but users can buy Android too", iOS and Android are not completely fungible operating systems nor the hardware they come with. Competitors do not need to be 100% identical to be considered alternative products to each other. Xboxes, Playstations, and Nintendos have different hardware and software but they are all competing in the gaming console market.