Smile, you might be on a police surveillance cameras, according to TED:
“A very unsexy-sounding piece of technology could mean that the police know where you go, with whom, and when: the automatic license plate reader. These cameras are innocuously placed all across small-town America to catch known criminals, but as lawyer and TED Fellow Catherine Crump shows, the data they collect in aggregate could have disastrous consequences for everyone the world over.”