As a member of a team, I also understand that pay differential is a potential source of tremendous discord. While everyone instinctively understands that some roles earn more than others, it's definitely better for that knowledge to be general rather than specific. I don't think that radical transparency about comp would promote good morale, in general. In this case, secrecy about pay is compatible with psychological well-being among employees.
However, I'll have to say that I agree with the regulators here. Its one thing for social decorum to dictate the secrecy. It's another for the company to have an official policy about it.