Why Flat-footed people not allowed in Military Jobs?

Flat foot people don’t usually get into the army because of not only the boots they have to wear, but the Army has to travel by foot a lot. There are already multiple foot problems in the Army and a flat footed person would have many more problems with their feet and possibly hold up their unit. Having flat feet has nothing to do with firing off a rifle.

The above is not true. the doctors at MEPS will tell you if your flat feet are disqualifying or not. If your flat feet are symptamatic (painful) then they will disqualify you, or if you have ever been prescribed custom orthotics by a doctor. If they are asymptamatic (not painful) then the doctor will tell you if you can join or not.

source: http://www.army.mil/usapa/epubs/pdf/r40_501.pdf