There are plenty of people who value their privacy...but if they do, that carries into their work life. People are consistent about things they value (whereas if they are uncertain if they value something or not, they can be inconsistent in that area)
The fact is, she wants her privacy from you.
Personally, I would describe her behaviour in this area as very secretive.
My phone does not have a pin, and I leave it laying around. I don't care who sees my bank account. I don't care if things I say behind peoples back gets repeated to their face. That is to say - Your girlfriend is the very last type of woman I would want to end up with...
...but it's up to you to know how you are, to know how important this is to you, to know if this type of behaviour is good for you - and to make decisions based on such.
As a side note, make sure you consider long term consequences, and long term happiness (unless you're just using her for sex). Anything else usually leads to bad decisions.