I thought you know how science works. What scientist thinks does not matter, it must be proven experimentally, peer reviewed and duplicatable.
I bet it was those “scientists” who determined that number.
Clearly there is a lot more going on then just %THC as it relates to effect. Scientifically proving that blood plasma levels do not correlate to degree of impairment would be great news for all users imo.
It's a valid point to raise, however, because the assumptions of the researcher are built into the testing model. If they don't know what they're looking for they won't build it into their model. Anecdotally, I'm the only researcher at my university with personal experience in this space. Not sure how we rank against other universities, I'm at a large SoCal research institution so probably more exposed than others, and I sit on our IRB so I see every research protocol that is approved (or not) at my institution.
For almost all researchers, the research is simply a means to an end--that end being another line on their CV. Career advancement and it happens all over not just in canna.
Minor point: science never proves, only disproves. More technical: we test the "null hypothesis," which is one of the many reasons those aforementioned assumptions of the researcher are so critical.