In that case, no, because there's hundreds (thousands?) of banks out there offering car loans and credit cards. It doesn't matter which one you get - most every bank is issuing VISA and MasterCard, so regardless of which one you get, you can do the same things with it.
If there were competing App Stores on iOS that a developer could distribute through, then yes, Apple could argue like you. As it is though, no, there aren't, because Apple is operating a monopoly.
"A manufacturer’s own products do not themselves comprise a relevant product market” and a “company does not violate the Sherman Act by virtue of the natural monopoly it holds over its own product"
That is the court's interpretation of the Sherman Antitrust Act - not mine. So, no, Apple does not have a monopoly. There are other App Stores out there - they just don't work on the iOS/iPadOS. Just like the restrictions on Xbox and Playstation. If it a customer can't access a product on iOS, there is plenty of access readily available elsewhere.
Epic has even tweeted to name the OTHER places its customers could go and play Fortnight if it wasn't in the Apple App Store. Per Epic, in 2019 only 12% of Fortnights revenue came from iOS. Twelve Percent!
Look, personally I think 30% for the level of service is too high. There are plenty of areas to improve in the App Store experience, which Apple can certainly implement if they choose to. However, Epic's argument is pile of crap and the precedent that may be set if they lose will make it even more difficult to affect change in the future. Change may be legislated, however that may be appealed and overturned (See tax battle in Ireland).
Or, they could win, opening the door to more crap lawsuits all over the place (who's to stop me from suing Whole Foods for not letting me set up a "pop up shop" free in their buildings to get access to their clientele with limited overhead?)
iOS and iPhones are not a public utility - it is Apple's intellectual property, protected by law, and Epic can't use any of it without a license from Apple, included the agreed upon terms. (See recent Qualcomm court victory.)