I think it comes down to number of registrants. If you have 20 men register, and 3 women register, it doesn't make sense to pull from the men entry pool to pay out the women pool, or the other way around (if that ever happens). It's the same in most sports with payouts like this, or royalties served from exposure. Just like the World Cup example earlier in the thread.
It's a nice fairy tale world, like equal pay for fast food workers etc, but theoretically the system doesn't work. When you work harder, or have more people enter in to the tournament creating a higher pool to payout from, payouts are just gonna be different.