To be fair, it's only privacy-violating if you have access to a way to lookup who owns the blue Toyota Corolla with license plate 1ABC234. The Driver Privacy Protection Act makes it illegal to disclose PII based on a license plate

A single bumper sticker or distinctive paint color or a dent in the door can be just as immediately identifying as a license plate at that level. Even in places where the plate is always the same for the car and doesn't change when it's sold, it's just a way to tell one vehicle apart from another.

Case in point, my user name is a license plate number of a total stranger, and I imagine you'd be hard pressed to even tell me the color of the car, let alone their name and address. I'm not asking you to doxx someone, but saying it's not trivially easy for the average person, even when considering the boatload of data broker information out there on every individual.