I was pulled-over for not having the sticker affixed in the designated areas on my car. Luckily, I had my stickers in the glove box and explained to the officer that I was just waiting for the PPF to arrive before putting them on. He let me off with a stern warning that you ARE breaking the law if you are in the HOV lane without the stickers. CHP officers don't care if it's a Tesla or any other EV. He said, at highway speeds, the only way to quickly verify is to look for the stickers. He also added, it is a $550+ ticket (moving violation, hence +1 pt on your record) not counting the cost to go to traffic school. Not to mention the penalty in insurance premium you will have to pay for 2+ years if you are not able to go to traffic school.
I don't know about anyone else but I hate paying fines, period. You get absolutely nothing for it other than wasted time and money. For those who drive in and out of HOV lanes taking their chances (not getting caught), well... good for them. Nonetheless, that ticket is going to poke right where it hurts when the luck runs out.