I'd be willing to bet the majority of those cited for driving high were smoking while driving
They just recently passed the law of 5 nanograms being the legal limit and the officers do not know how to test for it yet and/or aren't trained.
It also has to be a blood test which means they had to take you in.
They're not doing that on the suspicion you smoked earlier.
People are getting pulled over while doing it and getting caught green thumbed.