I have heard more than a couple drivers tell me they prefer to be high when driving as they are less anxious. And they feel they are much better drivers that way.
Of course, it doesn't enter their mind that their reflexes are so much slower because of it.
I'm curious though, weed can stay in your system well after the high is gone- a couple of weeks...what type of test can be given to determine if you are "high" at the time of driving and not just the lingering drug that can still be traced in your blood?
I don't believe such a test exists and that was one of the complaints of law enforcement.