Hey Levi, it's a great article: the wiki one. I always thought that's why some guys always head to the closet toilets versus the urinals. Interestingly also: would be more discussion in the article on what leads to this neurosis. My hunch is poor sexual education secondary to religio-cultural influence.
I know many men who grew up with the understanding that erections were ONLY normal when looking at the person that was your wife...or whom you wanted to be your wife. These guys were usually an only-child or grew up in homes with severely enforced modesty issues...usually, but not always, secondary to Fundamentalist religious understanding.
What the army did was breakdown this misunderstanding and show that everybody wakes up with an erection, gets a "piss-hard", etc.
Also, because of the competitive nature of many males: once they see someone hugely hung in the showers -- they do not want to be near him at the urinal, for fear of being seen as little or inferior.
Also, the erection problem: if guys are socialized that erections are normal only when looking at women, then popping a piss-hard at the urinal could, secondary to poor education, lead them to think that somebody might think they were gay if caught with even an autonomic erection.
Thanks for the article,
Bud