"One of the arguments at the heart of Epic's case is that Apple does not allow direct payments to developers or even promotions or information on where to make in-game purchases cheaper outside of the iOS ecosystem."
I've been suspecting something like this for a while. So it IS true that Epic is NOT allowed to inform the end user that they can make their in game purchases on another platform for cheaper than it would cost on Apple's platform. What's wrong Apple? Is Apple afraid of having an informed user base and actually having to compete on price? If Apple is confident that their strategy is the winning one, then why try to hide information from the user? I suspect the answer is because Apple prefers to embrace anti-competitive behaviors.
If it weren't for this aspect of Apple's policy, Epic could have just slapped a 30% Apple tax on top of the price and communicated that to the end user, and then simply left the decision up to the end user to make the purchase on Apple's "superior" platform or make the purchase on a cheaper platform. Thus, Epic wouldn't see a huge cut of their revenue go to Apple for doing an inferior service at cost level that is an order of magnitude greater than the cost Epic incurs when they run their own service for the other platforms.