like you said, it's one person's word against the other. how do we know she said no?
and polanski had a plea deal worked out, but figured he couldn't trust the judge after the judge had deceived him before. polanski had served some time, which the judge had promised would be enough. but then the judge then changed his mind and wanted to put him back in jail. there really was no reason for him to stay.
and yes, of course it has to do with politics. switzerland is under a lot of pressure right now from the US regarding their banking procedures. maybe they needed a high profile case to prove that they are friends of the US.