In only a few years, the surveillance start-up Flock has installed more than 100,000 licence plate reader cameras across the United States. But a grass-roots movement upset over privacy concerns is fighting back – even going so far as systematically vandalising the equipment. The first time he decided to trash one of the cameras, a self-styled vigilante wearing all black and known as Nomark, says he was “super nervous”. Now, after disabling about 30 of the devices near his home in the...