I have a personal experience with the harm that ubiquitous recording of location data can bring, even when you don't do anything wrong.
When I was in college, I was called to the police station and accused of breaking a glass door in the dorms. I knew NOTHING about this. I told the police I knew nothing about the event, but they continued to press me. They asked me details about where I was that night (many weeks prior), and I had difficulty remembering where I had been. To make matters worse, I originally thought the day in question was another day, so I ended up giving information about my location that was incorrect. If the police decided they didn't like me, they could have easily pressed charges for lying, even though I thought I was telling the truth. Luckily, they eventually believed me and I was let go.
How is this related to license plate readers? Well, the only reason they suspected I was the person who broke the door was because my ID card had been swiped at around the same time the door was broken. Simply because I was present near the time and location of a crime committed weeks prior, I was accused of a crime and nearly accidentally perjured myself. (Don't worry; I know now to never talk to the police!)
If we start tracking everyone's movements, this sort of thing will happen more and more often. You will EVENTUALLY have driven by a place where a crime was committed. You may be called to account for your being nearby, even weeks or months later. When the police ask you why you were there, will you remember? Will your answers satisfy them? Will your general unease at being questioned make you appear suspicious? Will you fumble, and say things that contradict yourself, making you appear even more suspicious?