The license plate itself isn’t the issue. The state want cars to have an easily visible identifier? Sure, whatever makes sense from a perspective of being able to identify a car and its likely driver at the moment when it's actively being used for a crime or for traffic enforcement.

The problem is that this state mandated visible identifier is then used by them to constantly track where you go. So the question is do you have the right to not have the government tracking your movements and keeping logs of everywhere you’ve been for months or years, especially when you’re not currently suspected of any crime?