Because you seem to think that having sex with four men is much more distasteful than the two men she agreed to have sex with.
To a prostitute (a WOMAN)I doubt if she really was offended by the train of men. I think she was more than likely mad that she didn’t get paid. Thus the crime of robbery.
To any normal thinking man or woman, your line of so-called reasoning is sick.
Rape isn’t based on subjective “distastefulness.” It’s an objective legal thing centering on consent. Otherwise, I daresay, a whole LOT of innocent men would be in trouble.