As has been repeated, men have pretty clear physical advantages - especially in the area of muscle mass, but I would say a lot of it is social and mental. Testosterone and "male-dominance" play a big part. You get a group of males together and you see a lot of attempts to one-up each other. You get a group of females together and there is less of that push to compete, though it's usually more of a supportive atmosphere.
I think this is also a large part of it. Although halfpipe/park snowboarding isn't the same as alpine racing, and they have different physical demands, you still don't see nearly as large as a skill gap in skiing as you do in snowboarding even though the physical differences are largely the same.
I think there just aren't nearly as many women who are interested in taking their snowboarding to that level. This is anecdotal, but for example, among my friends, all the guys push themselves to go further and further, while all the girls are pretty content cruising down greens and blues. I think I'm one of the more serious learners among my girl friends, and even then, I have NO desire to backflip onto a rail, or double rodeo (or backflip) off of a kicker, like they show on videos that pop up here.
So really, it's our own fault that we're not doing crazy tricks... but I don't really care. I'm just out to have fun, my sense of accomplishment is personal. It would be cool to be a model/athlete like Torah Bright................... but eh whatever, who cares
EDIT: And I don't do pushups on my knees either. And I can do more pullups than many fat tubby guys in PE.