App Tracking Analytics
Flurry examined the daily opt-in rate of users due to its integration with over one million mobile apps. The irony of a tracking company tracking anti-tracking is not lost on this author.
For international iPhone users, the opt-in rate is approximately 11-12%, while in the U.S. that number is lower at about 2-4%. This is important because the setting Allow Apps to Request to Track in Settings > Privacy > Tracking is turned off by default. When this toggle is turned off, iOS automatically blocks them from asking and tracking.
With such a low adoption, advertisers are (and have been) concerned. In one example, Facebook has displayed a message in its apps for iOS 14.5 users, asking them to allow Facebook and Instagram to track you to keep these services free.