Facial Recognition Tech firms have been helping themselves to pictures of people's faces with few legal restrictions, and they're using the imagery to build their facial recognition software. As Fortune's Jeff John Roberts writes: "Consumers may be surprised at some of the tactics companies have used to harvest their faces. In at least three cases, for instance, firms have obtained millions of images by harvesting them via photo apps on people's phones." Fortune
This is nothing special or new. Over the years millions (billions?) of people have voluntarily uploaded their selfies to Facebook and/or Instagram. Many users tag faces on those photos and the images are also linked to account data. If a Facebook user uploads a photo of him and his friend and subsequently tags the faces on the photo then Facebook also has knowledge of the face of the friend. Even if that friend has no Facebook account himself! In this case the friend wouldn't even know that his face is in Facebook's database.
The genie is out of the bottle with this technology and it has long been so, it's far too late to attempt to put it back in.