Residency trained physicians can't do them without paying money and receiving special "training" from the state. Chiropractors can pay the same money, get the same training, and be allowed to do them. Random person off the street or even my MA, who I'd say has more medical training on conditions that would be dangerous when driving an 18 wheeler, can't pay the money or take the class or do the exams.
I especially love it when these unqualified providers send me a form to sign that any of the actual medical problems they have will not affect their driving.