I’ve worked with sailors for 30 years. There are some 18 year olds who can be trusted with a nuclear power plant, there are others who cannot. The same goes for a firearm.
They are all part of a discipline structure in the military that does not exist in high school. Without that chain of command and accountability, the immaturity comes out.
Nuclear power plants and M-14s are lemons and oranges. A bunch of 18-19 year olds being “supervised” by a 21 year old NCO isn’t exactly adult supervision. So when or if they make it back from Afghanistan they should be prohibited from buying a semi auto AR? Yeh uh no! :-)