Because german and western allied front propaganda is strong
You could say that but its both when Japan or Soviets involved (Countries that didnt sign the geneva convention) these things become hard to find, I cant find Americans helping Japanese Soldiers or Germans helping Soviet Soldiers (unless its 1939 and theyre invading Poland together) when both America and Germany signed the geneva convention but there is Chiune Sugihara that I know of (https://en.wikipedia.org/wiki/Chiune_Sugihara) but would you consider this helping the enemy?
When you look at World War 2 and read everything about it you have to admit the Eastern Front and the Pacific was much more Brutal than the Afican or Western Front