Honestly, these costs are very reasonable considering what you get.

The real crime is that Apple takes more as its mandatory fee and is only storing and moving bits. A good with essentially zero marginal cost.

Fulfillment is hard.

And, as much as people hate it, advertising is real value for a business owner.

And given the high cost of financing and holding physical inventory, Amazon's referral fee is worth it for faster inventory turnover.

Apple is the enterprise that borders on criminal. 30% to move bits. I haven't looked it up, but the margins on Apple's fees have to be outrageous.