Well, unless you're completely brainwashed in luxury beliefs, it is pretty obvious that legalization would increase the prevalence and frequency of usage.
This is trade-off that any rational person could predict.
> it is pretty obvious that legalization would increase the prevalence and frequency of usage.
Except that's not at all what happened, something mentioned multiple times in the article.
> No Effect from Legalization: The rate of drivers who tested positive for THC did not change significantly before or after legalization (42.1% vs. 45.2%), indicating that legal status did not influence the behavior of those who chose to drive after use.
This is trade-off that any rational person could predict.