I think capping fees would make it even worse, it would entrench the practice as acceptable.

Allow sideloading and the price should move towards the equilibrium price. Which very well might be 30%, since Google manages this despite allowing sideloading.

The tricky question I would say is the accessibility of the alternative stores. First there is the default/non-default install thing, we've seen how it worked out for Microsoft. Then there are all the warnings/toggles about unsafe external apps. This is much more difficult, since it's quite useful for security, but at the same time it makes it much harder for alternative stores/apps.

Visa and MasterCard charge somewhere between 1-3% (depends who you are and the details of the purchase). PayPal charge around 5%. Some two-way marketplaces charge upwards of 40%.

I think Apple is providing more value than PayPal, but less value than a two-way marketplace.

For me, 30% is extortionate and predatory. 5% is too low for the value they provide. 15% is quite high, but it can be justified given the value adds (advertising, content delivery, reviews, last resort QA, security etc).

I think the fees percentage should not be capped. Apple should be free to charge whatever they want. The main problem is the second issue you mentioned. That way apple controls devices without the owner of the device having any say in the matter. That should not be allowed. It is my phone, I paid for the hardware and software. So either let me install whatever app I want, or open source the whole thing so I can flash my own ios compiled from github.

If it became possible for consumers to side-load applications, the iPhone (and iPad) would lose what is in my opinion one of its biggest positive selling points: that Apple is acting as gatekeeper for executable code.

As soon as that capability exists, my elderly parent's and elderly in-laws' iPads will quickly fill up with malware and scamware like their desktop computers routinely used to.

And before you argue that you could choose to not open that pandora's box on particular devices. But as soon as enough developers decide that getting around Apple's fees is worth the effort, use of it will become commonplace and potentially unavoidable.

The high order bit is the inconsistent, capricious nature of the app review process. Hey attempted to participate in the established detente of "paid service, can't buy it here, wink wink" and Apple somehow decided this was the time to squeeze.

Clear, consistently enforced App Store rules, from a perspective of Apple desiring the best apps possible.

I don't really see how Apple would be able to justify the 30% cut if sideloading was possible.

Hmm, like Google does ? Even that isn't a panacea, see Epic giving up on distributing Fortnite by itself.

Sideloading makes the other point moot I'd say since competing third party stores would appear?

I don't think it does. F-Droid exists but is essentially totally unknown on Android.

Only because Google is relatively freer than Apple. Android users and devs don't feel too constrained by Play store rules. If play store were to start behaving like app store, you can bet money f-droid, amazon store and others will rise in popularity.