"I've got nothing to hide" is a straw men.

It's a fact that people who are being watched, or even who think they might be watched, behave different then those that think they are totally private [1]. So in order to discover who you are or how to deal with certain problems you encounter in life, you have to have an environment with the least amount of external influences possible. Having no prying eyes avoids self-censoring and conforming your thoughts or behavior to what you think that is expected by others. This way privacy is the matrix of diversity, new idea's and insights and a way to free ourselves from doctrines and repression.

[1] https://en.wikipedia.org/wiki/Panopticon

You should forward her this as well:

http://chronicle.com/article/Why-Privacy-Matters-Even-if/127...

And TL;DR: "the banality of evil". Even if a majority really have nothing to hide, a large minority of innocents do have something to hide. To not cared for them is inhumane.