Why does the game treat US forces as less capable?

[EnemyAce]

I started to wonder what exactly matters how infantry can survive or fight if there's no nationatily faction? Weapons, gear etc.?

[mr_clark]

Well, as far as I understood the game Morale and Exp is very important as hte unit then is less likely to get routed.
Apart from that I think the 'US Problem' is that the infantry units of the USA are quite small (menpaower wise) in comparison to other countries as it's mainly mech inf, and then also often splitted into a 4men inf unit and a 2men AT team...