For example, in most top universities, they give roughly the same leave to new fathers as new mothers. New mothers use this time to care for their baby, but many new fathers use this time as an extended sabbatical/research leave. Their wives take care of the baby for the most part, and they work on their next book.
Then when it comes time for tenure review, the men who did this have accomplished more than they would have if they hadn't had kids (and more than some faculty who are mothers, who spent their leave with their baby).
So when everyone gets the same treatment, that doesn't necessarily reduce or eliminate disparities — and in some cases it can exacerbate them.