Sure, but that's not that big a barrier. First, there are some pretty good classified mugshot datasets in existence. FB's, for one. Second, you can get some m

Sure, but that's not that big a barrier. First, there are some pretty good classified mugshot datasets in existence. FB's, for one. Second, you can get some mileage out of just matching images to eachother. One or more cameras track an individual to get multiple angles. You may not know the individual's name, but you will know that it's the same person walking past the cameras every day. Third, you can always target a limited set of faces. Don't casinos use something like this for persona non grata?