Actually, no it's not and I really don't like to see people say this crap. I've been driving stoned for over 40 years now and I haven't had a single accident. While I've never been drug tested I can state with confidence that I would have failed one at any time of my adulthood. While I am able to drive and function in public while having consumed enough weed to stun an elephant I do agree that there are some people, mostly those new to getting baked and those who react strongly to THC, who shouldn't imbibe and take the wheel. If they do, I have no problem with the law nailing them to the wall. I really don't worry about that because I'm a patient, responsible driver and I don't attract the law, even in our well-equipped Mustang.
Being anesthetized with alcohol and being stoned and inexperienced are two completely different things but they can similar results when behind the wheel of a car.
Sorry but this is just wrong. Being stoned is similar to the risk of a shift worker i.e. 1.5-2x more likely to get into an accident. I'm not sure if there's an accurate roadside test out for this now as just simply having THC in the system doesn't tell enough.