Putting My "Progressive" hat on...
Really the minimum wage should facilitate a minimum acceptable standard of living. If 18 year old single male Bob, get's a job, surely we can agree that the minimum wage to provide him with the essentials in life is less than Molly the town slut, that has 6 kids by 4 different men. So, Bob, being a male and young and single can easily get by living with several male friends, in a not so great section of town. Bob, doesn't have to worry about getting raped, bob is a male and bigger so it's okay for him to live in a more "affordable" area, plus bob has less expenses, he doesn't have to buy tampons! Bob can be alright on 9/hr in most areas. Molly, in order to live at the same standard of safety for her and her kids will need on site security, and live in an area with low crime rates overall. Being a Mother, molly needs to be in top form, so will require the best healtchare, we wouldn't Molly to get ill, who would take care of those precious children! So, Molly will require 80/hr, just to live at the same standard as Bob!
This is fair, both Bob and Molly are actually working for the same quality of life.
This is the future, equality at last.