> Why did Apple do this, though? If you recall, Apple's stance on privacy is quite recent. The tech world has a short memory, but I remember Apple being caught red-handed slurping data from user's iPhones not so long ago. Also, unless things have changed (honestly, I haven't followed), Apple tracks users through their native apps, because you're pretty much obligated to go through Apple's SDKs for many things, and they require a tracking ID, which brings revenue to Apple.

This is incredibly misleading. Apple has been mostly criticized for allowing apps to collect excessive user data--for example, apps could access contacts at first without permission. It has been slowly shutting down these methods, as the realization has sunk in the the more open environment of Macs and PCs is just not appropriate for mobile phones. For example, apps in iOS 13 cannot access bluetooth or Wifi information by default, since it was being used to infer location.

Apple does of course collect some user data, e.g. for Siri or app analytics. But it's all painstakingly disclosed and its practices around differential privacy, deletion, and so on are quite good.

The tracking ID was Apple throwing a bone to ad industry and app makers, when it shut down far more precise ways of tracking users.