Women are too smart to make the same as men
I would argue that women are smarter than men and realize that to make that additional 5%, they have to give up 25% of the fun in life. If you look at a lot of the high paying jobs, they come with high stress, long hours and high risk. I think that many women look at those positions and think "It's not worth it". (There are exceptions of course)
Picture that you are at a gathering with 5 males and 5 females. On the table is a bowl of salsa that has been spiked with hot pepper extract.
The first male will walk up to the bowl, dip a chip in and take a bite. His eyes will water, his nose will run, he'll grab anything you offer to put out the fire burning in his throat. The other four males will each think ... "It can't be that hot. This guy must not be able to handle his spice."
The second male will approach the bowl and ... amazingly, the same thing will happen. The remaining three males will think ... "It can't be that hot. This guy must not be able to handle spice." This will repeat until all the males are complaining that everything the eat tastes hot and their tongues feel burned.
The five women will continue enjoy themselves, thinking ... "Hrmmm, that salsa must be very hot, I think I'll skip it. It's not worth it."
No offense to @papa-pepper.
Interesting theory. They do say that women take jobs with more flexible hours which usually translates into lower stress. Maybe youre onto something :P
More awareness of the impact emotions have over time can make this decision instinctive in women. In my opinions men aren't given as many tools to explore emotions through life, calculating the long term cost of overworking could be more difficult.