Perhaps it's also that, in the U.S., sci-fi has long been considered to be a subgenre of fantasy, a view this line from the Oxford Dictionary of Literary Terms (OUP, 2008) tends to support: "Science fiction is a form of literary fantasy or romance that often draws upon earlier kinds of utopian or apocalyptic writing." I used to edit a column on SF/Fantasy novels, and if an unlucky reviewer used the phrase "science fiction and fantasy," we'd sometimes get angry letters from readers saying, in effect: "There is no science fiction AND fantasy! Science fiction is a form OF fantasy!"