Employer side negotiation tactics and better metrics to close the white/black pay gap

Usually when I see graphs measuring the racial pay gaps, for reasons we all understand, they compare whites and blacks at the same title, experience, and year. But that ignores one of the ways I have seen employer side negotiation tactics maintain and drive pay disparities. Here is the situation: A reasonable person understands that wages cannot be forced to decrease year after year as compared to inflation or cost of living. But many workplaces/stockholders expect exactly that. So what happens when wages are failing to cover rent, healthcare, and basic necessities? People with options turn down the jobs. People without options (or worse options) take them. What did this look like when I was hiring, and salary setters (in my case HR) refused to increase the salary bands? White males turned down the jobs or stopped applying. White women took them but left quickly. Black women applied, accepted them, and stayed. I did not see any black male candidates. So, nice that the workplace was diversifying, but quite bad that black people were being taken advantage of. I think a metric that could be internally adopted and tracked to prevent these outcomes is: ( inflation adjusted black wage yr5) /(inflation adjusted white wage yr1) for any given position. I picked a 5yr interval because it seemed like a time period where meaningful change in salary and diversity could be captured. If the metric is less than 1, then you immediately know that something in. your company's practice is going wrong and that you are penalizing the black labor pool. Importantly, it gives you a number to back up the adhoc observation and to use to lobby for change. Please let me know your ideas for -improving this metric, -suggesting a different one, -and how to pitch these without getting fired/slated for a 'layoff'