Facebook privacy?

[Mr. Spontaneity]

OK, I'm new to Facebook. What I want to know is: Are there really THAT many private members on Facebook. Now I understand that you must be their friend to see their profile or be in the same network as them (doesn't always work). I am in two networks: My high school and Australia. I can get into almost everyone in my high school network, but only about 2 out of every 50 Australia network profiles. Is this because they have modified their privacy settings to friends only? I am just overwhelmed by the amount of privacy. And some people have public Myspaces, but make their Facebook private. What's up with that? So are there really that many private profiles, or am I using the site wrong?

All clarification is greatly appreciated.