"Mostly they are carefully trained to do exactly what they are told" That is another reason to be alarmed at this kind of episode - the idea that they might in fact have been doing what they were told to do.

In the same way my worry about that helmet "Kill 'em all" wasn't that there might be the occasional soldier who is screwed up or stupid, any large organisation is likely to have some like that, but that it looked as the label was ok by the army authorities, rather than being recognised as a serious breach of discipline, with very dangerous possible consequences.