How 's this for evidence women pay more for everything, and not by choice: http://www.businessinsider.com/pink-tax-makes-female-consumers-pay-more-2015-12
That article is based on the same study as the one you previously cited. The one I did my own research on based on the links embedded in the PDF linked to in that article as well as my own online shopping research.
It looks like the study had wanted their conclusions first then set out to find some data to back them up. Try it yourself, you'll soon find that the links don't make it easy to confirm the study's findings.
One thing that's weird in the CBS article is this quote from Department of Consumer Affairs Commissioner Julie Menin.
“We sent letters to the CFEOs all of the manufacturers asking them to change this pricing,” Menin said.
They sent letters to the manufacturers ? why on earth would they do that rather than send letters to the retailers ? If I can find both the men's and women's version of the same shampoo ( VO5 ) at a different retailer from the one cited in the study then that's evidence that the manufacturers are wholesaling the product for the same price with the retailers being the parties that are responsible for the price "differences".