[0] https://web.archive.org/web/20040418012411/http://astraware....
This provides no basis for comparison because the App Store has been the only way to install apps on iOS that whole time, so that changing can't have been the difference.
Moreover, the market they're monopolizing isn't the market for apps, it's the market for app distribution. So the relevant price isn't the price of apps, it's Apple's 30%. Which is obviously higher than in markets where there isn't a single-party distribution monopoly, e.g. payment processing is typically ~3%, various packaging systems like apt are free (or user can download binary from website as on Windows), and the binary hosting cost per user is negligible.
There is also a tying argument. App Store ties payment processing, distribution and curation together when the buyer might want different providers for each.
This has never been the case. You’ve always been able to side load apps that are either signed by an Enterprise code signing cert (used to be $300/yr), or your own developer code signing certificate ($99/yr). The former allowed for redistribution outside of the App Store.
Anyone who claims Apple prevented side loading clearly never bothered to research that claim.
What reason should it be for?
Price of the same "Angry Birds" in 2018: $0 to install, $1.99 per 80 gems, no way to disable in-app ads or purchases.
Free-to-play is an increase in price.
I completely agree that prices on Apps have come down but that is just what happens when a new market is created. Supply and demand has to set in. Developers are guessing what people will pay at first and if they find they can sell millions more if they just drop the price to 99c then they might just do that. In my opinion the Apple App Store has had very little to do with those prices coming down.
While I do admit the App Store was incredibly innovative and has ushered in an era of new ways for developers to create/distribute/monetize this stuff it is hard to deny that if there was any competing way to load Apps that the 30% fee Apple collects would stand... not to mention the many practices that developers (and consumers) disagree with that Apple regularly does such banning apps that may compete with their products or somehow upset them.
Edit: I don’t want to come off as overly negative here, I love Apple and their products. I am simply arguing that a little competition here would do consumers good.