This is intentionally not PII. You accept this burden when you decide to register a vehicle.

Keep in mind you don't need to have a license plate or to register a vehicle to drive it only on private property.

Your license plate is required to be readily visible so that it can be used to find out who the registered and, presumably, responsible party is.

Consider if you skip out on paying for parking at a garage, where you agreed to pay the fee by parking there in the first place. How is the business supposed to identify you to collect the money owed?

Otherwise, how else would automatic private toll roads know where to send the bill?

In Michigan, I believe the law only permits someone to request registration details for certain listed reasons. They don't verify that, but if you're caught submitting a fraudulent request, you can get in trouble - I don't know if it's a fine or crime. Probably depends on the circumstance.

PS Hello from Grand Rapids!