here in NJ they drive over a HD color camera thats a live feed to a 32 inch monitor. the guy see's it as he drives over, they are looking for it here.
the commercial truck lane they use mirrors on a stick to look underneath for the cat or cats.
they dont do a sniffer test any more or check blinkers or the horn or the wipers or the tires lol im not kidding, but you must pass the cat visual, and the obd2 scan.
a commercial truck everything must work as it should still. they test the whole front end, the brakes the tires the lights every last thing. no sniffer tho.