“However, when I ask the owners/dispatchers of actual trucking companies they all state the same reason as to why it is so difficult to find drivers:.....”THEY CAN NOT PASS A DRUG TEST”
Unfortunately, it is just a guess but maybe why the drug test factor is so big in finding truck drivers has to do with the population cohort of who is attracted to being a truck driver - why do so many attracted to that work have drug issues.
And, I know the full drug issue is more than just illicit drugs.
I have a nephew who has been suspended from driving a long haul truck more than once for a drug issue - he’d ignore taking his diabetes drugs and doing so would affect his blood sugar levels, resulting in problems driving. His employer required diabetes blood tests from him before every run and demanded to see he had his prescription drugs available for the length of a run.
When he was younger he had the other kind of drug problem - illicit drugs, and I think the length of that experience chemically altered his brain wiring, especially in critical decision making.
This is a problem in the saw milling industry too. Being around large band saws, planers, debarkers, and other heavy machinery can be dangerous. People occasionally die. If you can not pass a drug test, they do not want you working in their sawmill.
This is also why many sawmills no longer allow you to tarp a truck on their property, even with a tarping station. This is because drivers have fallen off of the top of a loaded flatbed truck when they were trying to tarp a load. Again, this has resulted in deaths. FYI, a tarping station is where you put on a harness and hook into an over head arm that keeps you from hitting the ground if you fall off the trailer.