step 1 Tracking and profilling step 2 selling data step 3 profit

Android and ios use completely different methods. For example, they listen to frequencies that are inaudible to us and, for example, TV advertising plays an inaudible sound as a trigger for Android/IOs in addition to the audible sound. To impose targeted advertising in order to allocate devices even without a network, etc. They wouldn't actually need backdoors as they get more than enough information as it is. But I don't want to imply that I don't expect backdoors there, because this has been proven in any case and often enough.