> “The CAT also ruled that app developers passed on 50% of the overcharge to consumers.”

This is complete nonsense. App companies set price based on willingness to pay. If Apple allows custom payments alongside IAP, you might get a temporary gap (naturally <30%) to steer people towards in-house payments, with harder refunds etc. But as soon as they're no longer required to adopt IAP their own prices will go back up to exactly what they were.

The vast majority of Apple's app/IAP revenue is from "mobile game" companies. You think they won't enjoy a 42% increase in iOS revenue (1/0.7=1.42) by keeping prices at a level consumers have already accepted for years? There's no "lower sales" tradeoff, customers are used to those prices.