Here is a good overview of dozens of studies that have performed on subject.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2722956/#S3titl...

The tl;dr is Cannabis absolutely impairs the core skills you use when driving, but also raises your awareness of your impairment so those under the influence tend to drive more cautiously. The result is in simulator studies cannabis shows a clear negative effect, but in functional studies, its more of a wash.

Please fully read and understand the resource you linked

> Experienced smokers who drive on a set course show almost no functional impairment under the influence of marijuana, except when it is combined with alcohol.

And the conclusion that the lack of functional impairment is due to increased awareness of impairment is merely speculation and is not based on any empirical result.

I don't even understand how this is a question in anyone's mind.

Because studies show that Marijuana results in no functional impairment in test courses? Maybe you should learn to trust data and science rather than just your preheld beliefs that aren't necessarily rooted in sound logic or reasoning.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2722956/#S3titl...

Have you never seen anyone super stoned before? What studies do you even need beyond that? Yeah there is a scale before people shouldn't be driving, and this device will help enforce that line. It may take time and work, but better than nothing.

Once again, your personal experience and anecdotes aren't necessarily reflective of reality. Personal anecdotes are the worst form of evidence there is. Read the actual study, so that you may learn something. Your miniscule personal experience is in no way rigorous.

The study contradicts your assertions and does so in a rigorous controlled study. Obviously that holds more weight than your anecdotes or statements that have no empirical or logical basis.

From the paper you linked

> Experienced smokers who drive on a set course show almost no functional impairment under the influence of marijuana, except when it is combined with alcohol