Internet is incredibly complex. There is always a way to reach someone's information via Internet and privacy becomes more uncontrollable when you integrated your all social networks with each other.
Danah Boyd and Alice Marwick say that in their articles "Many of our fears and concern regarding safety stem from the ways in which the Internet uncovers many things that we were previously hidden".It may not be true for all people but I agree with that it works like that for many people, called 'fear of privacy'. People can not control their privacy since the Internet is getting more and more evolved day by day.
Facebook is very popular all over the world. More than most people have an account on Facebook even if they do not use regularly. And when you post a photo on Facebook, your privacy settings may not be enough to hide it from people who are not friend with you on Facebook. Even the sister of Facebook's founder got that problem as they said in
the Atlantic Wire "don't expect to hide something if you do — everything can be shared and re-shared these days".