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.