“There’s also the reason that it’s nobody’s business if an adult drinks alcohol or smokes pot.“
Well, with pot, there isn’t any clear/legal definition of what “under the influence” is.
Writing as someone who was injured twice (avoiding serious injury only by luck) by someone doing one-hitters all day in a factory years ago who wasn’t following procedures, I think that this is an issue.
Wrong - several legalizing states have set blood concentration limits on THC just as is done with alcohol.