I believe that license plate readers have the capacity to violate privacy and steal your personal information. If someone happens to be a sophisticated hacker, there is a world of things they can do with just a simple license plate number. Once they have access to that, they can easily find you name on the web and the possibilities after that are nearly endless.
There are plenty of things I think people don't understand about their privacy. Facebook for example, is an company where you give all your PERSONAL information to them and suspect nothing. While they are making money on those information by selling them to companies, you get nothing in return. Here license plate readers actually doing good things for the society such as catching crooks, rapist, drug dealers.... It helps to build a better society. Of course, it will take a picture of your license plate and its location, however It doesn't know who drive the car and the information about that driver. Police needs data in order to do analysis to catch bad guys. What would you do if you have your stolen or your kids got kidnapped. You call the police to help and all they can say is: "We tried our best to find him/her, but we can't do it at the moment because it's out of our scope" . Would you feel better if the police say this : "Sir/ Mam, we got a lead base on the license plate reader and with the description of the car thief or kidnapper". Think about it. I wouldn't want to hear the first sentence EVER.
License plates are public property. To drive on government-created roads, society trades in certain rights. If you do not like it, you do not have to drive. No one is granted autonomy in their cars. License plates are specifically there to identify the driver in a vehicle, so reading them makes sense.