Apple was arguing that the “iPhone users” / “consumers” did not have standing to sue, but that the app developers did have standing to sue. They were trying to get the case thrown out of court.
The court disagreed, because the costs (commissions) were passed on to the users / consumers.
“To evade the court’s test, all Apple must do is amend its contracts,” Gorsuch wrote. “Instead of collecting payments for apps sold in the App Store and remitting the balance (less its commission) to developers, Apple can simply specify that consumers’ payments will flow the other way: directly to the developers, who will then remit commissions to Apple.”
and...
Apple argued that the lawsuit’s focus was the 30% commission, something the company said is paid by the developers, not the app purchasers. Although the consumers said they pay for the commissions through higher app prices, Apple said those are the type of “pass-through” damages barred under the Supreme Court’s 1977 Illinois Brick v. Illinois ruling.
Apparently, Roberts & Co agreed with Apple??