Seems fair to me, 27% commission implies 3% for card handling fees, to level out to the same 30% developers would have to pay doing things the intended way.
All this talk of using "alternative payment systems" just seems like a way to skirt around paying Apple commission.
I think the big sticking point is whether smartphones are a generic, standardised thing that requires some level of guarantees for the end consumer on accessing software of if each smartphone is one of many products in a broad category that all have different restrictions and limitations. Essentially the "you have a choice, just use Android" defence. I'm not saying which one is correct here, just that this seems to be the specific fork in the road between differing opinions.
I thought that the justification for the 30% commission was the tightly integrated payment system, and not just the fact that you can install the app in the first place.
That's definitely one aspect of it, but I've always thought most of that fee is simply for the "privilege" of being a part of the Apple ecosystem, being mostly profit for Apple with a portion going towards the hosting, distribution of the App, search/discoverability aspect.
I can definitely see why this fee and it's associated lock-in upsets many consumers and developers. It's clearly a divisive issue right now, and I am unsure we'll see any resolution to the overall narrative until the EU/US forces Apples hand.
All this talk of using "alternative payment systems" just seems like a way to skirt around paying Apple commission.