Then inform them that you don't have the power to imprison them but the government does.
I have successfully changed the mind of a dozen people in about 90 seconds. You have to shock people out of their stupor.
Me: You should care about these things. X: But I have got nothing to hide! I don't care. (Then I get the look, "Do you have something to hide?") Me: OK. Since you have nothing to hide, please give me your Facebook password so that I can go through your FB inbox. Also, your Gmail and Skype passwords would be good to have, since you have nothing to hide.
Never fails to work.
I think the issue is that people tend to place certain "trust" with the government and that their information won't be misused and have this notion that the government can't do no wrong. But they tend to forget that there are people in a government.