"If "friendly fire" occurs because of the confusion of war, why have only the Americans killed people with friendly fire? Why haven't the British?"

Sadly, we have. One Challenger managed to hit another last(?) week, blowing the turret off, killing two crew & seriously injuring the remainder. However that was someone in the middle of a ground battle making a mistake.

One has to seriously question how the fly-boys manage to make so many mistakes, though, especially in situations where there is little or no hostile fire coming at them. Such as that idiot who not only managed to shoot up a British unit, but did it twice, having possibly previously passed over them a few minutes before.