And a lot of those top-level ones are rather entrenched by owners of the businesses & their family connections, which are often
dominated by male-only thinking. The top tiers are often a very insular world all its own, it's no surprise they're changing so very slowly. Sad, but not surprising.
Pay-gaps measuring across the board are rather meaningless, aside from showing a cultural bias for hiring. There's definitely a significant pay gap, but a lot of articles like that one take male-income / num-males and compare it to female-income / num-females. More point-by-point comparisons show a smaller gap per-job (I usually see 5%, sometimes 10%. Significant, but not 25% significant like the article lists). For psychiatry in particular, it's also become an over-crowded field; to compete, and to get the average-joe on their bill, the average-joe psychiatrist must lower their cost.
edit: as linked by tokenadult, I point this out for consideration of the results, but not as an explanation: http://en.wikipedia.org/wiki/Simpson%27s_paradox#Berkeley_se...
I'm not discounting the entire thing by any means, most of the purpose in the comment is because the issues around child-care are utterly ridiculous. I've run across a fair number of men who have run flat against (spiked) brick walls in their attempts, followed by rather massive repercussions for simply trying to be single fathers (lost jobs, criminal investigations (finding nothing), near-eviction from their community, etc). I've not heard of parallel situations for females as bad as many of them have encountered, in relatively recent years. Going more years back, certainly, things were blatantly downright misogynistic in many areas.
As to the last paragraph, that's a better way of putting it than your original post. I overall agree :)