@Grumpy Ole Codger If it's not covered by the Constitution, nor enshrined in Federal law (applicable to all states) then each state decides their own.
Here in Virginia, it's annual, whether you need it or not. At least for bikes it's not onerous, as there is no emissions check, and all they do is walk around the bike while you're sitting on it, saying "Lights, high beam [nod]; left turn signal, other turn signal. [walk to the rear and as he passes] "Horn". In the back it's parking lights, both turn signals, and brake light. $12 and done.
Next door in Maryland, the inspection is only done when the vehicle is purchased -- waived for a new vehicle.
In less populated areas, there is no inspection at all.
"It depends"