Um, graft. Like all other cases of protectionism. There was once a problem and someone suggested regulation to fix it and now that the problem is gone the regul

Um, graft. Like all other cases of protectionism. There was once a problem and someone suggested regulation to fix it and now that the problem is gone the regulation remains. There are two fundamental issues here. 1) Why is commercial driving complex 2) Do we need a rent-seeking monopoly industry to solve the issues for us? The answer for #2 is a resounding no.