All this preaching about a gender wage gap but not a single factual case of two people, one male, and one female, working together where the man is paid more or the woman being paid less. . Name any company or business that does that. Name the boss.  Name the man . Name the woman. The authors don't take education, seniority, work time,  job skills, and job type (which includes levels of on-the-job safety risk)) or even financial investment risk into consideration.