I've got to disagree about your belief that young people can not be effective managers. The military routinely turns young college graduates into officers and gives them leadership responsibilities. That system has been successful in the United States for more than two hundred years.
The main difference between the military and the private sector is in the preparation. The military has a specialized training program (OCS) specifically tailored for leadership principles that all applicants must pass before becoming officers. That lasts for several months. And, for young officers, there's a great support system of experienced officers and NCO's who can give them advice.
Private corporations generally don't offer training and mentorship programs any more due to cost cutting measures. It's common to have people promoted to management positions with no training whatsoever. And the closest civilian equivalent, an MBA, seems to breed arrogance.