For many jobs, there's a uniform that employees are expected to wear.
Whether it's so customers can better identify who works there (not that they always do anyway) or so management doesn't have any unpleasant surprises in the morning, it's clear that a lot of organizations maintain that there are benefits to standardizing how people are dressed rather than letting them wear whatever they want.
However, there's a growing understanding within both public and private organizations that it's possible for uniform policies to be too rigid and that any benefits that might come from them aren't worth discriminating against someone on religious grounds.
And while it seems that certain branches of the United States military have understood that for a while, a new step in Air Force policy should result in fewer headaches about headwear for all involved.