“It’s Apple’s platform, they can do what they want” I hear people say constantly. That would be true if Apple kept the iPhone as it originally was - a completely closed platform only capable of running first-party apps. The moment they opened the platform up to developers to compete on they created a marketplace and have to abide by all the rules and regulations that govern a marketplace.
Imagine if Walmart imposed rules on Gillette that said, in order for Gillette to sell its razors at Walmart, they had to follow specific rules. Gillette is not allowed to offer their razors or refill cartridges at a lower price at any other store, including their own. They’re not allowed to advertise that you can buy replacement razor cartridges anywhere besides Walmart. And Walmart will sell its own brand of razors and place them in more prominent locations in the store. Sure I could go to Target but Walmart is closer and more convenient and this unfairness that occurs in the background isn’t readily apparent to me as a consumer.
The app store itself is less of an issue as is the draconian rules Apple imposes on developers to participate in the store, alongside the deeper level of integration it gives its own services that aren’t available to similar third-party offerings.
It’s not about security, Apple can mandate strict signing for any app installed on iOS similar to macOS.
It’s not about convenience with in-app payment. Apple can mandate that developers offer Apple Pay as a payment option (which apple does *not* take 30% out of) and have consistent dispute/refund rules.