I'd say the red trousers of WWI fall in the same category as the "ping" of the clip ejecting from the M1. Something everybody heard about and is endlessly repeated regardless of facts.
Given that in 1914 units still tried to maneuver by platoons, while leapfrogging and using cover was a basic tactic, the red trousers would not be much of a giveaway as some would think. troops maneuvering in numbers and firing at you don't really need a telling marker to indicate where to shoot at, besides trousers don't make a good aiming point anyway.
Yes they would be a giveaway to observers, but so was the later blue uniform and even the khaki or field grey of other armies often stood out against the terrain they were fighting in. Humans are very effective at noticing movement and negates most forms of camouflage, and why troops who use camo for a living either don't move or try to do so in a way that doesn't arouse suspicion and adopt poses that make it hard for you to spot them.
As for the other uniforms, most came from a time where the average soldier was likely to miss a formation of men standing right in front of them, let alone pick out individuals with a nice aimed shot through the heart.
I also found the Hessian headgear callout incredibly funny as if people had no clue as how to behave when dealing with obvious problems.
worries about not losing his rules stuff.
