@skilly, you are absolutely incorrect. @chilliban, good job proving my point.
I know for certain simply because I've been one that likes to keep my car looking new in some cases and therefore waited much longer to put the plates on the car. One time, I think I went about a year. Never got pulled over for it. I did get pulled over for another violation. Honestly, not having the plates on the car saved my butt. The officer knew he had to write me a ticket for something. My not having plates on the gave him something to write me up for while letting me slide on the moving violation.
The point however is, it absolutely, 100% was a correctable "fix it" ticket, as I already noted in my prior post. If the car is registered and is legal, it's simply a fix it ticket for not displaying the license plates. The question however wasn't about license plates, it was, if Carpool Lane stickers would fall into the same category? Logically, if license plates are a fix it ticket, would think the same to be true for not displaying Carpool Lane stickers, assuming the car has been registered for the HOV lane and is legal. This one however, I'm not certain of. Still hoping someone can answer it with certainty.