It seems that the best reason many people can think of to protect privacy is that they break minor laws and don't want the government to know! Which is about the weakest argument in favor of protecting privacy that could possibly exist.
In fact, that only reason that really ought to need to exist is that many citizens place great value on it. Since that is obviously not good enough for the statists among us, let's analyse the underlying logic of the statement "what do you have to hide".
- Asking the question openly implies that having something to hide is a bad thing. For example if I had a secret love of romance novels (I don't) I would not want that fact made public. That I would want that fact concealed, that I would carry those novels hidden deep in the nether reaches of my breifcase in no way makes me a bad person.
- The more subversive assumption behind the question is that the state (i.e. "we, the people") has the authority to surveill individuals regardless of their status as a law abiding citizen. If the state cannot search an individual absent probable cause, why do we assume that the state has the authority to
- track the location of individuals
- compel individuals to report their whereabouts
in the absence of probable cause for suspicion of wrongdoing?
Regardless of whether one has a right to an expectation of privacy when using a public road, requiring law abiding citizens to prove that they are law abiding runs counter to the very foundations of the democratic traditions that allow us to claim that we are "free". It is one thing to have a speed camera which records the presence and location of those individuals who actually break the law but having systems which record the presence and location of individuals regardless of whether they have broken the law or not is profoundly intrusive.
That it is open to abuse by state officials or people with illicit access to the information is merely a sidelight when compared to the importance of reigning in government intrusion into places that it has no business or authority to go.
Note that I use the word authority in relation to this issue. The state has the power to do pretty much whatever it pleases. It's authority is a very different animal.