>...and then tags it with your name...

Even that's not wholly necessary required. If they can obtain data from your own Facebook app (or an app using the Facebook SDK), it can place you in that area around the time the photo was taken and given it's friends you have connections with on Facebook, it's easy enough to surmise it's you without the necessary confirmation.

Seems very Orwellian, to be sure, but not out of the grasps of the end-goals of data harvesting/profiling.