This seems part of a larger battle being done against Apple. Weird, but I think true.
But, yeah, if Apple's rules are you have to run things through their payment system, and they have a darn good system, and they want a cut, is Epic going to lose their poop over the 'cut' that credit card companies charge? If they were listing and selling on ebay, would they declare jihad on ebay for charging fees for selling on their service? Does their CEO piss holy hell at paying for cap fare, or Uber drivers? DO they rant at the charges for concert tickets, and dry cleaning?
At some point, you have to realize that to live in Apple's ecosystem, you have to pay for the privilege. They knew that going in. Apple curates their app store. Google really doesn't. Stuff gets refused probably on a daily basis. That costs. ALso the payment system, ApplePay, it costs Apple to run that too. Forcing Epic's customers to use Apple Pay isn't a hardship for their customers, it's a feature, right? (Does Apple require Apple Pay, or some other secure payment option?)
Whatever. The next time their CEO is speeding because he doesn't believe in rules, he can explain his theory of how he gets to decide, and no one else does.
Epic is being childish.