>>508891329 (OP)American military physical training actually has a large preference for average/short people. The cardiovascular and muscular requirements for most calisthenic tasks scale proportionately to height. Basically, it's harder for tall people to jog their bodies the same distance for someone who is shorter. It's harder to do burpees, pushups, pullups, etc. Not to mention there are explicit height limits in the Army, Navy and airforce concerning the operation of different vehicles or equipment.
>tldrthe taller heights can probably be ascribed to less demanding physical activity and restraints.