On iOS tracking and access to personal information is always opt-in. It’s literally a modal alert asking if you want to give permission when an app requests to access the IDFA for the first time.
Apple’s own apps don’t need to display the prompt because as per their privacy policy they don’t collect or use information for tracking purposes (which is also visible in the privacy labels of their apps in the App Store).
> Apple’s own apps don’t need to display the prompt because as per their privacy policy they don’t collect or use information for tracking purposes (which is also visible in the privacy labels of their apps in the App Store).
This is the privacy policy [0] of an example of their app, Apple News. I quote:
"Advertising
In order to deliver great content to you from leading publishers, Apple News is ad supported. If the Personalized Ads setting is on, Apple’s advertising platform may use information about your account, the topics and categories of stories you read, and publications you follow, subscribe to, or turn on notifications for to serve ads that are more relevant to you. We may also use information about your subscriptions to personalize your ads on the App Store."
In this case, you're referring to "Data Linked to You". "Data Linked to You" is based on the account you used to sign in to the News app + your activity within the news app - to create suggestions within the News app.
This does not allow Apple to track you from the News app e.g. access the IDFA of the device, sharing it with third parties or other apps.
It's made clear from the policy which I took the liberty to quote here that Apple News tracks your interests and uses it to personalize ads not only inside the same app but also Apple's App Store. Same policy states that whether you are logged in on the app or not, you will still receive ads.
They claim they do not share this data with other third parties but they sure as hell use it for their own advertising ecosystem.
Using an opt-out is completely different from using third party ad blocking technology and is much more friendly. I can set the IDFA opt-out on my father's iPhone and nothing will break, but if I set him up with ublock or dns blocking and it starts breaking websites, he will be totally confused and not recognize what's happening. Also, using hacks to block tracking is not 100% reliable and allowing the user to have a specific option like Apple does is better for the user.
And since you brought out the opt-out option, one can also block Facebook's trackers through uBlock and/or DNS filters.
The defaults are what matters. From the same Wikipedia article,
> Users can opt-out of IDFA via the "Limit Ad Tracking" (LAT) setting (and an estimated 20% do).
80% users never change the defaults.