They do not expect high schools or colleges to provide the prerequisite training. The transformation is remarkable. Entering the training, many are out of shape and lacking in discipline. Exiting training, their bodies look like they have been carved out of granite. Their appearance, conversation, manners, posture, and clothing all befit a Marine.
Some people call it bearing.
No civilian training program comes close. There is a very long history of applying principles of military leadership to civilian, and especially business leadership. THE ART OF WAR written by Sun Tzu over 2,500 years ago is often cited as a treatise on leadership. Sun Tzu argues that leadership in war management must be separated from leadership in state government. He calls for professionalism.