All developers pay rent in the form of annual developer fees.
Apple needs to charge more then, otherwise Amazon, Starbucks, Bank of America, Uber, Netflix, Instagram, etc. are all freeloading since Apple doesn't get a cut from them for any transactions. Apple knows this yet they're perfectly fine with it.
Those companies don’t make anything directly from Apple’s platform. Digital goods/services/content benefit directly from Apple’s platform which acts as a middleman… user buys Apple’s device, Apple provides a platform for the developer. Apple is in the middle of that relationship and feels they deserve something for that transaction that happens on their platform.
Most developers get around that by making money indirectly from pushing ads.