Well, her word during this trial wasn't very convincing since she had the date wrong as evidenced by her phone records, called him 75 times or so after alleged rape, took a year to go to the police, etc. So maybe his lawyer decided that he said, she said was good enough.
I read one article on this and it appears that he was a “cad”, to use the old fashioned term.
The girls had sex with him, hoping to get ahead in Hollywood/show business. He did not follow through on his promises, implied or explicit. They got mad and made the rape accusation(s) to get even.
Still it would seem at the moment of penetration, they were willing participants. Especially the ones making the accusation who were supposedly raped at the playboy mansion and came back for more. In some cases it was simply oral.
What was funny is what was left unsaid in the article, which is why I remember it. In our modern world they could not say the girls kept going back because they were trading sex for opportunity, so they left unsaid the motivations of the women in keeping in contact with Crosby for a year or more. These women were at venue that allow good looking young women to hobnob with celebrities. Gee I wonder why that was, do these young women have brilliant insights to offer? Kind of funny, they would not say what was going on.
Of course this is all based on one article, there may be facts I did not read or am unaware of.