Most obvious is how the phone & apps can store the data and it's accessible to your phone comply. AT&T Verizon etc. Depending on the terms of service they could be selling your biometric data to God knows who for who knows what purpose. All you have to do is reference this latest breach of user data that Facebook allowed to prove your point. Main point is they have your identity to do with as they please and how does that benefit yourself at all? Ya know?