There are several complex answers to this question, which I'll delinate in a moment after I've expulsed my bowels.
Aah, that's better. Anyway, first is the premise that this is a wage-decrease in gross. Actually, there is a tighter differential between the linear progression of wage vis. rank vis-a-vis the male workers' rank progression, such that, for there are more women in positions of lower seniority, and job-hopping is far more common with women given the lucrativity available to them, so it is true that a higher proportion of women receive lower pay than their male counterparts. Male loyalty, however, in this regard, is taken advantage of; to get women to stay in a company to ascend position at all, so each promotion confers a steeper pay-rise, such that female pay exceeds male pay at a lower rank and so proportionally (if not in absolute terms), more women than is warranted receive beyond-pay-grade salaries. It obfuscates a matriarchy, no video will openly and admittedly explicate the obvious especially when it comes from a feminist position.
No, this isn't propaganda, I'm not high, I'm not schizophrenically paranoid, women are obliged not to mention this secret deed of the trade, and so lie in deliberate underestimation of their paycheck to male counterparts when asked.
(Edited 2 minutes later.)