Regarding employment opportunity, etc.: it’s a fair objection, but that’s not something that I need to prove. It’s something that you need to prove in order to show that the cause is sexism. I’m not saying that the cause can never be sexism, I’m saying you can’t prove that it is and it’s up to you to do so, because it’s impossible to prove a negative. Otherwise, we’ll be hunting a sexism-of-the-gaps for as long as both sexes have not achieved complete parity in everything, which means we’ll be doing so forever.
By the way, the feminist scholar Dr. Christina Hoff Sommers has concluded that a wage gap does exist to some degree even if you account for everything we know to account for, but that gap is 2% rather than 23%, and 2% is pretty close to the margin of error. So we can conclude that sexists exist here and there, but it’s not pervasive. If we get rid of those bad apples, the “raw” wage gap will still be about 20%. Incidentally, in a UK study, among unmarried single men and women in their 20s, women slightly out-earn men; so the anti-female sexists don’t seem to be doing a great job in the current generation. It’s once children start to happen that the gap reliably appears. There’s not much we can (or should) do about biology.
Regarding the “Pink Tax,” the products used as examples almost always have significant differences in the male and female versions. Because even if the active ingredient is the same (in the case of hygiene products and the like), men seem to be generally okay with smelling like the active ingredient, or like the kind of chemically simple and cheap-to-produce odor you’d find in industrial cleaners. Women generally don’t seem to be okay with this, and demand more chemically complicated (and hence more expensive) products, which therefore cost more money. If you want to pay less, buy the male product, which is functionally equivalent.