Ideally the people writing the policy could provide the sources that we could scrutinize. I just keep hearing politicians and advocacy groups saying 77% for literally decades now. I'm willing to accept there is a gap. I'm not willing to accept that this number hasn't moved for years.

Here is one saying women (25-34) earn 93% -- apparently not controlling for the actual job at all.

https://www.pewresearch.org/fact-tank/2021/05/25/gender-pay-...

Time after time it seems "pay gap between men and women" is conflated with "pay gap between men and women in the same job". Then there are the made up numbers that are the talking points.