http://news.independent.co.uk/uk/transport/article334686.eceGovernment has absolutely no right to track the movements of private citizens unless they have reason to believe that those citizens have committed crimes (and are going to commit more crimes), are committing crimes, or are going to commit crimes in the near future (or have serious plans to do so), and have convinced a judge of that.
The idea of the government having enough cameras in place around a country to get accurate recordings of the movements of a single license plate over a number of years also is something to be extremely wary of.