Specifically, these big companies revenue share with app companies who in turn increase monetization via selling your private information, esp via free apps. In exchange for Apple etc super high app store rake percentage fees, they claim to run security vetting programs and ToS that vet who they do business with and tell users & courts that things are safe, even when they know they're not.
It's not rocket science for phone OS's to figure out who these companies are and, as iOS / android os users already get tracked by apple/google/etc, triangulate to which apps are participating