I agree with Abbiedrake. Hair length seems to be an American issue. In Australia very few people could g.a.f. about hair length. In any workplace it’s okay, as long as it’s clean and kept in an OH&S safe fashion.
I would agree that the U.S. military has gone overboard with short hair. Last time I worked with them (2007), anything longer than a number two was frowned upon, and clean shaven was preferred.
Michelle