Re: Respect rather than arrogance
Dunnu about the UK, but from AUS nobody under 21 died in Vietnam. Age of draft was from 18, but draftees were 'from 18 up', then training, then not everbody who went to Vietnam died.
One of the lessons of WWI was that teenagers couldn't be depended on to stay awake on watch -- even with the death penalty for sleeping on guard duty. WWI boys lied about their age and enlisted at 16. WWII, the army had decided that they didn't want those kids.
One of the lessons of WWII was that people over 30 couldn't survive starvation or sickness, and by Vietnam, the army had decided that they didn't want those people. That reduced the average age at death, but by removing the top, not by dropping the bottom.