These reports tend to focus on measuring the outcome, because that's the measurable KPI.

It leaves as an exercise to the reader to guess the cause, and your comment shows exactly what i believed for years. "There is an inequality of outcome because people typically act differently".

I now realize that the gender pay gap is just the outcome of bias in the workplace... Whether conscious or inconscious. We must recognize them and actively try to counteract their effects of we want to reduce the gender pay gap. Something often criticized as "reversed sexism".