Did you know that has less to do with gender and more to do with ability? I can give a direct example that happened to me.
I worked with a lady about 10 years ago. We had pretty much identical jobs, job descriptions, and experience. Even the same education, both a bachelors degree. We even worked side by side in the same room. But I made more than her. Why? Because, as a man, when the side company that rented out tents, tables and chairs needed help in the warehouse for loading one of the trucks for a job, they wouldn't page her, they'd page me. I could do BOTH jobs. She could only do one. But on paper, our jobs were identical. But in reality, they were not. After a month, I told the boss unless my pay goes up quite a bit, I'm not getting out of my chair just like that woman never does. I got a raise after a month and a half of almost 25%. That is but one example I can think of.
Women also spend more money than men do. Men tend to be more frugal. Look at the population of shoppers at a mall in the middle of the day. 90% are women. OF COURSE they're going to have less saved up, they spend like drunken sailors. Look at the audience on TV game shows like The price is right. 90% women. They aren't at a job making money, they're on a game show. So of course their husbands will earn more and save more money than they will. Men also tend to work more hours at the same job than women do because women have to leave for kids, appointments, etc. The woman I worked with ALWAYS had somewhere else she needed to be. I was ALWAYS on time, every time and always arrived early and left late. She left for an hour every day for lunch, not one time in 2.5 years I worked there, did I ever leave the property for lunch. I ALWAYS brought my lunch so our customers were taken care of. I ate lunch at my desk sometimes, just so I could help customers who were paying my paycheck. The woman I worked with didn't give a damn about our customers. When that fat woman wanted lunch, not rain or shine nor sleet nor hail was going to stop her from leaving. (and 90% of the time she came back 10-20 minutes late from lunch.)
Men have better work ethics, period. I NEVER, in 30 years of being in the workforce, worked somewhere where a WOMAN stayed late to close. Oh no, EVERY WOMAN left RIGHT AT their off time. Men would stay late, often uncompensated, to finish up and take care of things for the next day. That went from the retail place I worked, to the airport, to dispatching, now to truck driving. It's always the same thing. There are also tons of jobs that women could do if they wanted, but don't want to get their nails dirty. So obviously men would make more than them in these areas.
Women also want paid leave when they have a baby. Men don't have babies, so men stay and work full time. While she'll be paid maternity leave, she will inevitably have to take sick days off to take care of her sick child. That's going to deplete her earnings for that position that a man won't have taken from his. It's the women that take the kids to the doctor, having to take off of work. Almost never the man. My dad NEVER took me to the doctor when I was a child, EVER, LIKE EVER EVER. It was ALWAYS my mom. My dad had to work. He couldn't do it.
It has nothing to do with sex pay discrimination, it has to do with men and women being VASTLY different creatures. Look what happens when a woman busts her ass and applies herself and works hard. Her name is Oprah, worth well into the billions. How many of the worlds richest people are women? How many of those woman started businesses and how many just inherited their wealth?