Collecting data in order to derive a unique identifier for the device is not permitted. Examples of this are: BSSID, SSID, wireless network information, Bluetooth signals, locally shared objects, advertising cookies, and other persistent identifiers.
Device fingerprinting is a covert tracking technique that circumvents user privacy choices; Apple's explicit prohibition is one of the strongest anti-fingerprinting stances by any major platform and directly protects users who have opted out of tracking.
Apple's App Review Guidelines directly affect what apps consumers can access, what data those apps may collect, and how they can pay for digital content — Apple's mandatory in-app purchase requirement means app developers cannot offer cheaper prices through external payment links on iOS. Consumers benefit from Apple's content and privacy review standards, which prohibit apps from collecting data beyond declared purposes and require age-gating for adult content, but have no direct appeal mechanism if Apple removes an app they rely upon. You can review an app's declared data practices by checking the App Privacy section on any App Store listing before downloading.