This analogy doesn’t make sense to me. This isn’t a bank transfer, it’s a purchase of a digital artifact. Is Apple wrong to ask for 30% of IAPs in Candy Crush? Because this seems pretty much the same to me.
So what makes digital artifacts (especially those that don't have anything to do with Apple's platforms) different from physical products. Would Apple be wrong to ask for 30% of purchased made through the eBay or Amazon apps?
It seems like it's their product and their right to draw the line wherever they see fit. They risked investing a lot of time and money into a platform that apparently now counts as best user experience. There is no ethical challenge, software developer gets access to wealthy customers thanks to Apple's decades of work.
Then don't use Apple - who is forcing you to build for their OSes? Your customers are there? Well maybe they have made a choice to be there for some reason. Respect that or don't go after those customers.
I have made a choice to use apple because I know all purchases for digital products go through iAP so my card details are never passed to the developer in any way. It makes me sleep better at night. I don't want other options.
I don't want to be offered the choice with 28-27% discount because it will make me share my creds (we know most ppl will choose the cheeper option and I admit I will do so as well from time to time).
I don't need the additional cognitive overhead because some developers are unhappy they have signed up to terms they don't like.
Honestly everyone that complains about the 30% so far hasn't given me a good reason other than greed. It's not a better UX, it's not a more secure option, it's not in my best interest (except the argument it will be cheaper but we all know that if possible most if not all companies will just pocket the 28-27%), it's not respectful of my choice of OS (again my reason is that I WANT the iAP as the only option).