When I was 19, I had a child & graduated nursing school in the same year, with no parental help. When I was 21, I bought my first brand new house, once again, on my own. I was hardly a child. Did I have the best judgement? No. Hindsight is 20/20, & no 21 year old has the wisdom & experience that comes from living on this Earth for 40 years.
People that age are asked to choose a college, major in a subject that will lead to a career, make all kinds of life changing choices. Is it only the ones that choose the armed forces that are "children"?
I watch my 21 year old daughter ( who, by the way, has been quite competant since around the age of 18), in college, living her life, choosing her major, her job, her friends, etc. & to let her go to be an independant person thrills me! To cut the apron strings & allow her to be a free individual makes my heart sing. But there is nothing drastic riding on her college, with the possible exception of our pocketbook
There is everything drastic riding on the young people that join the armed forces! People's lives ride on their dong what needs to be done & doing it right. Not all the US armed forces are 18-21 years old, to be sure! But the ones that are seem to me to be some of the most together young people I have met so far. They are focused & dedicated, & to me it somehow diminishes them to refer to them as "children".