The primary difficulty with rape is that the majority of it is committed by men who appear to be ordinary, even upstanding and decent members of society. Rapists have jobs, girlfriends, wives, children. They have friends who they play sports with and are kind and helpful to their work colleagues.
Women don't want to believe that men they know who are nice and normal might rape them.
Men don't want to send nice, normal men like this to prison.
And so we get the rape myths, the aim of them is to initially disbelieve the woman entirely (she's malicious, she's mad), if that doesn't work then the next best thing is to say that it was her fault and he didn't know he was doing anything wrong (they were drunk, she was flirting with him, they'd had sex in the past), if that doesn't work and it is accepted that the man raped her on purpose then the next step is to blame the woman (she was asking for it, what did she expect, she shouldn't have been walking on that street / out after dark etc). If there is absolute total proof that a man has raped, that all these people can't pretend that it was an accident, that she was asking for it, that he didnt know he was raping her, well then and only then should the man be prosecuted. But still, as he's such a nice normal bloke then he shouldn't be punished too much.
Exceptions are when people rape the very young or old, which generally generates outrage, or when the rape is accompanied by excessive violence, possibly murder. However there have been cases where even really vulnerable people (young children, women with learning disabilities) have attracted the victim blaming approach.
Incidentally I always find it interesting that outrage is reserved for women who are outside their childbearing years. For females between the ages of about 13 and 60, it seems to be "less bad". I am convinced that people also have an underlying idea that red blooded men can't help themselves. The thing I find really creepy is when people say (as they always do) that how could anyone rape a very old/young person, why would they want to do that. As if to imply that everyone understands why men want to rape females aged 13-60 and that to an extent it must be accepted that is what they will do 
ALL rape is rape, as soon as people start to think that one victim deserved it more than another then we are into very dangerous territory. This is why the language that people like KC use is so important, and what he has said has really set things back for rape victims.