Everyone on the App Store is paying the same fees.
As with any product the retailer markup should be taken into account when pricing. If the developer doesn’t think they’re making enough then they should be pricing their products higher. And if it truly is a monopoly the prices of everything on the App Store would be prices accordingly for everyone.
This is simply developers being greedy. Apple’s strength is its ecosystem and developers know what they’re signing up for. They just don’t want to pay for the benefits. But I can guarantee if they didn’t have Apple most of them wouldn’t be able to achieve anything.
Except Apple undercuts competitors such as Spotify, Netflix and can offer bundles because they do not pay the 30% cut. (I know they're not purchasable as IAP). Having a notification advertisement for Apple Music is laughable.
Then look a report shows Apple files a patent for on-demand cloud gaming services, maybe that's why they're not allowing xCloud and such 🙄