Do you know of any sources that talk about this? I tried to do a bit of searching and the closest I found was the .gov site [0] that did make a similar-ish claim, but was vague enough (at least to me, a non-lawyer), that it doesn't seem to rule out that every photo taken by an individual is copywriteable

>First, copyright protects original works of authorship, including original photographs. A work is original if it is independently created and is sufficiently creative. Creativity in photography can be found in a variety of ways and reflect the photographer’s artistic choices like the angle and position of subject(s) in the photograph, lighting, and timing.

I find it hard to imagine a photo taken by someone where it couldn't be argued that those elements exist. I guess the photographer would have to explicitly tell the court something like "no, I put no thought into it whatsoever, the camera was hanging off my bag and the shutter button was pressed accidentally". Like, if a human purposefully took a photo, then they have made choices about location, subject, etc. which have some element of "creativity" to them.

[0] https://www.copyright.gov/engage/photographers/