People with CDLs get drug tested at least a few times a year and often far more. They have different rules about how they have to behave in the case of drinking and driving versus the rest of the population.

Their livelihood depends on being a safe dependable driver and also there are levels of CDL, endorsements, that allow people to drive larger vehicles with air brakes.

As much as I am for anybody being allowed personal use of anything, I am simultaneously supportive of restricting the hell out of anyone who has ever been caught with a DUI. Personal use means you stay home and don't threaten anybody on the road.