What privacy expectation do you have in public acts with a state-issued placard?
You want a real story, delve into *private* use of this same technology.
"To spit on your hands and lower the pike; to stand fast over the body of Leonidas the King; to be rear guard at Kunu-Ri; to stand and be still to the Birkenhead Drill; these are not rational acts. They are often merely necessary." Pournelle