My guess is that the rape of strangers is usually about power and ego. Date rape and statutory rape are usually about sex. The three are mutually quite different, and using the same word to denote them does not increase their similarity. (It's more an attempt to harness our outrage against one crime to apply it to the other.)

Fighting back with one's hands to the best one's ability is probably a good defense against date rape, and will aid in the prosecution. Against stranger rape fighting back will probably only make the injuries far more severe; in that case, the woman needs to use a deadly weapon, and ruthlessly.