I'm sure there are plenty of ways for this to backfire, but I've always thought one of the most effective ways to eliminate salary bias is for companies to list a role's salary up front, in the job posting, before they've begun interviewing. That way the salary is roughly set before the gender, race, height, physical attractiveness (i.e. any qualities that can cause unconscious bias) is known about whatever candidate a company eventually hires.

Obviously it wouldn't outright prevent negotiating - you could still ask for $15k above what they listed in the job posting - but it WOULD help candidates navigate some of the smaller moments during the interview process that can unknowingly undermine their negotiating position (e.g. "How much did you make in your last role?").