It's not about having nothing to hide....

....it's about stuff not being anyone else's business.

"If you've got nothing to hide, you have nothing to fear"

That's the campaign slogan the UK used when installing millions of public surveillance closed circuit cameras.

I used to be in the military and one of the things we learn in the realm of information security is that one little piece of information might not justify any kind of protection, but if you put enough of these pieces together, you can build an accurate picture of what's going on and that can be a matter of concern when it comes to privacy. Professor Daniel J. Solove:

"By joining pieces of information we might not take pains to guard, the government can glean information about us that we might indeed wish to conceal. For example, suppose you bought a book about cancer. This purchase isn’t very revealing on its own, for it indicates just an interest in the disease.

Suppose you bought a wig. The purchase of a wig, by itself, could be for a number of reasons. But combine those two pieces of information, and now the inference can be made that you have cancer and are undergoing chemotherapy. That might be a fact you wouldn’t mind sharing, but you’d certainly want to have the choice."

Why privacy matters, the article.