I'm not going to argue or do research for you but narcotics impair your ability to function if you are a normal baseline human being. [spoiler]If you're some kind of super human good on you.[/spoiler] There are edge cases where a small dose can help focus but it's ridiculous to say drugs don't cause accidents. Stupid people exist in both the sober and stoned world. Stupid stoned people will be more likely to get in an accident that stupid sober people.