I guess my point is - so?
From a developer's standpoint, they are still paying 30% to Sony or Nintendo. You are telling me that they are not supposed to have an issue paying Nintendo 30% of revenue from a $60 game, but evidently have issues paying Apple the same cut (or even less, depending on whether they are on the small developer programme)? I don't see Tim Sweeney petitioning to get Steam or Epic Games Store side loaded onto my Nintendo Switch, where he gets to keep 100% of Fortnite revenue, while also hosting other developers' apps and charging them a commission.
And I too can argue that Apple has aggregated the best customers in the world thanks to the premium pricing of their products. This means that iOS users have more disposable income and possess a higher propensity to spend, meaning more potential revenue for iOS developers. In this context, it does not seem unreasonable for Apple to expect a cut for their role in growing the overall pie for developers, and for facilitating the purchase process (iTunes, biometric authentication, trust and ease in downloading apps), all of which add up to result in more apps being sold overall (and consequently, more revenue for them, even after the 30% cut).
So it's not that different from your argument that Sony and Nintendo intentionally sell cheap hardware to grow their user base. Both have their own ways of juicing app sales; they just go about it in different ways, and if one party is entitled to a cut for their efforts, then surely the other is too.
People are just too quick to scream "unfair!!!" when they really just mean "not to my benefit".