Asking someone out is difficult for everyone. Period. Some people get rejected more, others less. There's no universal answer for why some get rejected more than others.
But most of all, lets just go with this baseless claim, why does it even matter? Does blaming women make the problem go away? Does it improve the chances of your advances being accepted if you point out that women have it easy? Does it make you feel better to think that women don't have it as tough as you? How does that help you in any way?