I know that it is the case that the police and intelligence services can and do track 'interesting vehicles' using our technology but then again your movements can be tracked by looking at which mobile phone cells have logged you in their area of coverage so you could argue that its simply a more hi tech and therefore sexier system of police/security service informers.
I don't know what the answer is other than making sure that people are aware.
I did have similar concerns when I was contracting and people would ask me if I wanted to work for companies that supply equipment to the military and I know that some people are quite happy to work for arms manufacturers and they have no qualms about it and are only concerned with how much money they are getting.
I think that the only answer is to have people who are aware of the issues and are concerned about them working in places where they can attempt to ensure that the products are used in a responsible manner.