Because in the prompting case, the artist you commissioned isn't a human. Existing case law says you can't have non-humans holding copyright, because only human

Because in the prompting case, the artist you commissioned isn't a human. Existing case law says you can't have non-humans holding copyright, because only humans can be creative, and copyright requires creativity. In the case of works for hire, the human artist is contributing creativity so the commissioner can steal[0] it for themselves. But with AI art, there's no creativity to steal, so there's no copyright. [0] My editorialization. The rationale of what is and isn't a work-for-hire was not some principled decision but just a list of whoever wasn't in the room when the last major copyright law was drafted.