The difference here is that Google makes their money on iOS mostly from searches in the browser (Google pays Apple >12B per year for this functionality to be pr

The difference here is that Google makes their money on iOS mostly from searches in the browser (Google pays Apple >12B per year for this functionality to be promoted in the OS). When a user taps on an ad on a Google search in Safari, then makes a purchase on the advertiser’s website, that conversion is not defined as “cross-app tracking” so Google can record it and charge for it. When a user taps on an ad in Facebook and then is directed to the advertiser’s app to make a purchase, that is “cross-app tracking”, and Apple won’t allow that conversion to be recorded until after the user says yes to the prompt. Also, if the user clicks an ad in the Apple store, then makes a purchase in an app, Apple will happily charge the advertiser for that conversion without ever showing the user a cross-app tracking permission prompt.