I've never understood, and feel I have no intuition for, responses like this. What's the value added by this? Any excuse for exercise? Internalising that the sergeant is always right even when they're wrong? Or is "permission to speak" just a Hollywood affectation not really present in the military?

I honestly had no idea that this was a thing, but I guess it makes sense; colour blind people do see colour, but they see it in a different way, which could be leveraged to spot things people with normal vision don't.

I guess that also means that every squad should have one colour blind person, and camouflage should be designed to foil colour blind people too. Of course there are different kinds of colourblindness, which makes things more complicated.