Why is that though? I'd argue it's because the laws on sexual acts in this country depict women as victims and the men as the attackers. This filters down to how young people are educated and it then filters into how men and women act. Even now, with this desire for equality, there is still an expectation from women that men "make the move". It also leads to many men not reporting things which clearly are sexual harrassment/assault simply because it's not deemed to be "manly".
Basically, we can all be victims in some way, it just so happens that the way men and women tend to be victims in regards to this element of the law differs because of societal expectations of the different genders.
OK Dr Robert Winston, I agree that behaviour begets behaviour and that it starts with education, but the laws of this land don't really depict anyone as victim. They are about what it is right and wrong to do. That is just the basics.
As for 'making the move.' Aren't we moving on from that? I think so. Besides, many of the examples of casual harassment come from, as you say, previous learned poor behaviour. That's why trivial things are not trivial.
Would I compliment a woman at work about her perfume? No. Why would I do that when I'm at work?
Which begs the question, why is she wearing it in the first place. Answer: For herself, not for me.