It's not 30%, but a very large portion of VISA's profits comes from the fees they charge; VISA's fees are not capped to their "costs" of operating. VISA exists as a literal precedent that you can profit off a commission for a financial transaction.

The issue in question isn't whether Apple should be allowed to profit, it's whether they should be allowed to abuse their effective monopoly position to set their commission a literal order of magnitude higher than any other processor.

Apple has always argued that the 30% is not a payment processing fee. It's the App Store fee, which until today has bundled their payment processing fee with fees to cover their other expenses (and make them a tidy profit).

The argument over alternative payment methods has always struck me as odd for precisely this reason--throughout the Epic case Apple has made it clear that if they allowed alternative payment methods they would still charge the 30% fee for the other services.

Is 30% (or 27%) too steep for what the App Store provides? Probably. But fighting over the 30% as a payment processing fee is a huge misstep, because regulators will always take Apple's side on that question.

I don't see apple doing that either. This article says very clearly that the payment processing fee is 3%.