I read about this somewhere, I think there was a protest starting to get a fix for this.
I'm colorblind myself but it doesn't affect me.
You're friend should dedicate a bit of time to and remember that there is a difference in how your in-game model looks depending on what side you are on.The difference is there, i can't honestly think of an FPS that had features like you're asking feel free to tell me otherwise tho.
This is true, but in the heat of the battle I can see how a mistake can be made. Some of the models are pretty similar and I know that I myself rely on the colors now that I think about it.