are less safe than drivers operating a commercial motor vehicle in interstate or intrastate commerce on the day before the date of enactment of such Act, the Secretary of Transportation shall promulgate regulations for commercial drivers between the ages of 18 and 20, pursuant to this section. (e) No effect on license requirement Nothing in this Act exempts an apprentice from any requirement to hold a commercial driver’s license in order to operate a commercial motor vehicle. (f) Employer responsibility An employer shall not knowingly allow, require, permit, or authorize a driver under the age of 21 to operate a commercial motor vehicle in interstate commerce unless the driver is participating in or has completed an apprenticeship program that meets the requirements of subsection (c).