I think the Full Metal Jacket version of a drill sergeant is a thing of the past. They can get into your face like crazy but aren’t allowed to touch you. And I think they have all had to attend some version of charm school these days.
When I was in boot camp, it was the job of the company commanders (DI in the navy) to take a group of 80 kids from a variety of backgrounds and with an equal number of attitudes and levels of intelligence and make them into sailors. That means they have to learn to work as a team, they have to learn to just do things without endless debates or questions, and they only have 8 weeks to do it. Think about it. Everyone has to have the same hair cut. Everyone has to dress the same…not just the same clothes, but worn the same as well. They all have to make their beds every day and it has to be done all the same. They have to fold their clothes the same way. They have to walk in unison as a group. They have to run in unison.
They have to exercise as a group, doing only the exercises they are told to do, in the way they are told to do them, when they are told to do them. They have to eat together and have to be all done eating in 20 minutes. That isn’t 20 minutes from when you get your food, that is 20 minutes from the time the first recruit enters the mess hall until the last one leaves. All these things are done to take away all the individual styles you had before and get you doing it “the navy (or army, air force, marine) way”.