Commercial driver and pilot could maybe be better described as licenses. Those have recurring medical requirements, and CDL holders can be picked for drug testing at any time. Strangely most of the flight docs are ignoring the FAA disqualification item of taking a medicine within two years of it being released. At this point, most commercial and military pilots should be grounded for taking the new virus shots. The two year requirement is reasonable to protect flying public from things not found in rushed medical studies, like heart attacks.

MSHA part 48, or others, is useful to be allowed to be unattended on a mine site. The scope and size of some mines, and the operations and equipment, are something to experience. Of course, the mine owner must want you to be there.