But it's all fixed costs. I don't see how the 30% change anything.

Say you need 100k profit after Apple's cut.

Scenario A: Apple takes a third of the App Store revenue. You need to sell in-app purchases for 150k. Scenario B: Apple takes no cut. You need to sell in-app purchases for 100k.

So the claim is, scenario B would be the dream, but scenario A is "nearly impossible"? What is fundamentally different between 100k and 150k revenue, if your expenses are fixed? This doesn't make any sense.

The comparison to Uber doesn't make any sense either, their costs aren't fixed. If they want to double their income, they must double their work.