Comment by neodymiumphish

Former law enforcement officer here. I can say that when we conducted surveillance, we weren't allowed to use equipment that wasn't common for normal people to use. So for example, I couldn't use some sort of long-distance microphone to overhear a conversation between two people in public because a normal person wouldn't have that same type of technology. I think this applies in this context to say that a cop just scanning and logging every single plate that traverses a certain area is outside the bounds of what we'd consider lawful for normal surveillance. Alternatively, if a normal person would just sit down and write down every single car description and plate that passed by their house or any other public area, a cop doing the same thing would be reasonable. The scale of modern data collection for police is whats dangerous to individual privacy rights.