Having spent some considerable time in the training arena working with folks. I can make some guesses on this...
I'd imagine it has much to do with almost no-one, especially new folks but there are others, who cannot follow the rules of engagement that have been posted.
I agree completely with the need to train with the leathality at 100%, so much so that I'm going to have to set up a "Head-to-Head" or take the squad into the dueling arena.
A possible solution would be to eliminate the effects of friendly fire altogether or turn on the "kill-shooter."