Legally speaking, in many places women ARE NOT, in fact, capable of rape. Alabama for example (ya, I know, but I'm down here at the moment) has no provision whatsoever for a male to press rape charges against a women, under any circumstances that I am aware of.
Unless there is a truly level playing field -- that is, the same expectations, responsibilites, liberties, and punishments -- there can never be 100% equality. Every female (for example) admitted into the
military by passing the MUCH less strenuous physical requirements for females only strengthens the notion that women have weaknesses which must be accommodated.
Not to get off on a
women in combat thing, but it's true. Letting girls off easy implies by default that there is something to let them off on.
I got way out in left field here, and I'm gonna get in trouble. This is pretty much the same argument that got me in trouble when I said that a woman would never be President until it was socially acceptable to hit girls. Don't get that one started, no it's not ok to hit anybody, and that's not the point.
But as long as special protections and privileges exist for females (and I include the socially defended right to act like a dumb ass in with this) there will always be males who view that as justification for chauvinism.