My thoughts exactly. A non-researchable tag should a huge red flag to the mindermast, er, mastermind criminal.
Exactly, and that's why a properly prepared undercover vehicle will be registered to a fake name with a real address, and the vehicle license plate will trace back to that information.
Evidently, it didn’t occur to the government drones that implemented this...
Good point. Criminals see a car they think is surveilling them, they run the plate. It turns up non-searchable, bingo, it's a cop car. It would actually work better if they had phony addresses in nonexistent towns. At least it would look "real".
Which is why the "official" reason for having them is not likely to be the real reason.
If I was REALLY an undercover cop who was afraid that somebody would run my plates to get my address, the LAST thing I would want would be for the plate search to come back as "confidential/restricted". I would want the plate search to come back with my cover name, and some plausible address. And I would want any mail sent to there to be forwarded to me at the police dept. If it was anything but a ticket-avoiding scam, then mail would be sent to an address which would then forward to the police dept.