I've explained it before in these threads, I'll try one more time:
Apple charges 30% across the board for initial app purchases, in-app purchases, and subscriptions. This is arguably reasonable for purchases of apps (Apple's handling distribution, billing, taxes, security/anti-theft, etc. across hundreds of countries - I've heard multiple highly placed people in the industry say it's reasonable), it's probably a little high for in-app purchases (though, if there were no App Store, there would be no in-app purchases in the first place, because there would be no apps), and is, indeed, pretty high for subscriptions (and this whole sentence is simply my opinions on the pricing, obviously). But... if any of the three avenues for collecting money had a substantially different deal than the others, the developers would all tend to flock to using that method (whether it was a good fit for the app and for the consumer - anyone want to pay monthly subscriptions for calculator apps?) in order to maximize their profit. The other avenues for payment would effectively cease to exist. So, they have historically needed to keep the price the same without exception. Yes, they have recently instituted the bit where subscriptions go from 70/30 to 85/15 after the first year. This doesn't upset the Apple cart (so to speak) very much, because it is a good deal for legit subscription services like Netflix and HBO (and Spotify, if they played along), but very few calculator app developers will find people willing to subscribe for 2+ years just to get the developer a better cut after the first year. So the rest of the App Store is unlikely to slide towards subscriptions because of this new rule - you have to have an app that people will genuinely want to subscribe to for multiple years, to benefit from it. I was actually kind of surprised by how slick and simple the 85/15-after-a-year rule is, in this respect.
Say Apple did what you suggest, let everyone use outside payment methods in apps, while still keeping their pricing at 30% for initial app purchases and Apple-serviced in-app purchases. What happens then? Eventually, nearly every app would switch to free-in-the-store-but-pay-us-through-our-website (because, of course, companies would like as much of the money as possible to stay in their hands). At that point, the App Store has nothing actually for sale, they only have "free" apps (no cost to download and the developers collect their money offsite), and the App Store brings in no income - it becomes unsustainable and perhaps eventually goes away (it does get crazy amounts of traffic, and that does cost quite a bit to maintain). Is that an outcome you want?
How in the world can Google allow 3rd party payments whereas Apple resorts to censorship? Because that's what it is, Apple censors developers about informing users they can subscribe directly. Google doesn't. That's a fact.
