recently read a study about this, smoking pot vs alcohol in coordination, sensory perception and reaction time. It found booze was much MUCH worse. Not saying I want pot heads out on the roads driving.
OK going to look for link to that information now
"If it was available at bars then you'd probably instead be saying that you'd prefer to encounter someone high on cocaine on the road rather than a stoner or a drunk."
I base the observation on past experience with college friends who were fairly heavy smokers. A "high" of any kind is going to involve sensory distortion of some sort... if that weren't the case, there would be no reason to seek it out, it would be no different from everyday experience. As far as auditory and/or visual hallucinations are concerned, I don't know what you've smoked in the past, but it sure wasn't straight up marijuana. Based, again, upon personal experience, someone who has consumed large amounts of alcohol has severely impaired reaction times and motor coordination in general, and has greatly reduced inhibitions which leads to very risky behavior, behind the wheel of a car or not. Marijuana is, in my observation, more of an inward thing, yourself and close friends. Little impairment of motor skills, increased inhibitions which would imply a lessened likelihood of risky behavior, behind the wheel or otherwise. Cocaine has its own problems, chiefly among those problems would be that it is highly addictive, unlike marijuana. So, this attempt to create the appearance that I'm just some sort of easily-dismissed drug apologist doesn't hold water. If you're opposed to all mind-altering substances on principle, that's fine by me; I would hope that you could see your way past that opposition to understand that there actually are merits to this discussion.
Alcohol is a CNS depressant. Cannabis is a CNS stimulant but tends to relax, which is why it is so effective on migraine headaches (smoke pot and that headache is gone).
Cannabis has no effect on reaction time. In large amounts it does have an effect on focus, but in smaller amounts it has the effect of strengthening focus.