The information is out there. You can make it illegal to look, but it doesn't matter.
Consider that a shopkeeper can recognize frequent customers by their face. Our brains are made for face recognition.
Now obviously that's at a different scale than automated plate readers, but the information is there. We just took for granted that no one had the willpower to memorize a million faces. Our privacy was guaranteed not in law, but in practicality.
You can try to ban it, and you can maybe ban municipalities from using it, but the information is there. Anyone can just set up a camera by their house or business and collect the same info.