Facebook changes privacy settings for millions of users – facial recognition is enabled
nakedsecurity.sophos.com/2011/06/07/facebook-privacy-settings-facial-recognition-enabled
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
Most of the rest of us found the option in our privacy settings was "not yet available", which meant we could neither enable or disable it. We simply had to wait until Facebook decided to roll it out to our account.