A cursory Google search comes up with some shady websites that sell similar tech, but it would be a nice DIY project to make a licence plate screen that can be changed on the fly (e-ink based maybe).
Has anyone tried it?
You put it on the plate so that it cannot be scanned but if police pulls you over it falls off.
“Officers are always looking for uninsured vehicles,” said Surrey RCMP spokesman Cpl. Scotty Schumann. “The officer was very surprised when he saw a valid B.C. license plate magically lift into place after they had passed the toll cameras.”
Even with paper tickets, if you paid with a credit card there's now a perfect record: Jim Smith got on at the Fruitvale station and got off in Fremont, stayed there two hours, and then came back the same way.
Also, it's a little doubtful colors can be recognized in all light conditions (at night, in a tunnel, etc.)
And if the car is simply parked (vs. a road check), does it matter that it's "flagged"? What could happen? There would have to be a warning somewhere for the car to be impounded, or to send officers to wait for the owner to show up. Very unlikely IMHO.
Family member of mine actually got in trouble because the dealership typed the wrong color into the registration paperwork. The color on the registration didn't match the actual color of the car therefore it was considered illegally registered and the car was impounded during a routine traffic stop.
I believe that license plates used to be made of metal with reflective coating and ridges (made by prison labor?) but today on the street I am seeing what looks like white paper with black lettering?