I'm pretty sure the only reason we don't recognize this, while we do with movies, is that there aren't rules governing who's credited and what their credit look

I'm pretty sure the only reason we don't recognize this, while we do with movies, is that there aren't rules governing who's credited and what their credit looks like, as there are with movies. You don't get "Story by X, written by A, B, & C, based on characters by Z", and instead one or maybe two names are on there—you do sometimes see a writer credit (separate from the more prominent "created by") on some of those long-running series where the original author stopped somewhere along the way, or two listed for outright collaborations between known authors. If book writing operated under the same rules as screenwriting, this would all be a lot more visible.