The true genius of Facebook is it's practically impossible to not use it, even if you're not signed up. If anyone mentions you, or happens to post a picture with you in you're in it.
The same applies for Google, where if you happen to be in the background of a photo which isn't shared but gets uploaded to G+ quietly as a backup of an Android phone (which they do by default) then Google (and by extension the US gov) know where you were, as per their demo at I/O about 3 years ago.
The same applies for Google, where if you happen to be in the background of a photo which isn't shared but gets uploaded to G+ quietly as a backup of an Android phone (which they do by default) then Google (and by extension the US gov) know where you were, as per their demo at I/O about 3 years ago.