Interestingly, Apple puts tracking for its own apps behind another setting that ignores the global setting.
Unlike its competitors, Apple does not give users a choice about whether to send location data to Apple (if you want to see your location at all) or about whether to send app install and search information to Apple. Apple's devices are worse on privacy on every axis when you consider whether they give users a choice.
b) How would the App Store even work at all if they didn't store your purchases.
b) Most of the apps I use aren't purchased. Why should Apple know which apps they are? Apple's privacy-respecting (in actuality instead of in marketing) competitors don't require this.
b) I’m not sure if developer installs are being tracked by Apple. Are they ?
b) Developer installs on iOS are even worse for privacy than App Store installs, requiring an up-to-date payment method to associate with your device instead of just an email address or phone number.
I have relationships with Apple and Google. The line around what data usage is appropriate with those companies somewhat nebulous, and also somewhat a personal decision.
For instance - the paper you site shows that Apple and Google send location data from devices to the server. Those devices also both ship with functionality for things like mapping and local weather. So for iOS, you have to approve sharing location data (even for the built-in weather app and maps app) on an app-by-app basis. Android has gotten better about this over the years, but I don't know current state.
Facebook is (was) correlating detailed profiles of users who had no relationship with Facebook, through interactions with third parties that were not part of Facebook, and without disclosure. That is a much simpler line to draw.
Even then, Apple gave the user choice - and the users almost universally chose not to give that capability.