My feeling is that Andy Warhol's creation entailed greater effort, and certainly greater artistic expression, than Goldsmith's act of snapping a photograph of Prince. I guess what I really take issue with is that taking a photograph entitles one to copyright protection, when the image is directly created by a machine (the camera), while all the photographer does is point the camera and click.

In fact the USPTO recently opined against granting copyright for images generated by a machine (AI model) in response to someone's prompt (https://public-inspection.federalregister.gov/2023-05321.pdf). I believe applying this same standard (whether the standard is right is an entirely separate question) to photography should also preclude photos from copyright, because there is more artistic expression involved in prompting than there is in pointing a camera.