The women pay it, they just don't see the money as their employer deducts it form their pay first. As well, the employer has to pay a portion as well...which means that the women make less...because any company would take this into consideration when they choose how much they pay - they have a set amount they can afford then they see how much they will be responsible for paying and give the wages to reflect this.
The only difference is that as a self employed person you SEE and HOLD the money first then pay it...for employees they just get the left overs as their pay check! It's kind of like paying for something in cash versus debit/credit. If you just charge it you don't see/feel the impact as much as having to count out and hand over the cash! In the end it costs both the same (unless you charge it and don't pay before interest lol).