[ivanhoe]

How about 3rd parties collecting video feeds from a number of city locations, analyzing and face-recognizing people in them, cross-referencing that with other sources and building a database that they sell to private investigators and other interested parties. Combine that with license plate DBs and you can track movement of anyone both by car and on foot. Then you can get even more creative and cross-reference that data with marital status of people and find those who're seen walking the street or having a drink with someone who's not their partner (which we can find thanks to soc. networks). And boom, you've got yourself a mass-scale blackmailing tool that runs on auto-pilot. Possibilities are endless, and it's not even that hard to build something like that anymore.