That sounds like it is entirely the publisher’s internal policy, not at all related to whether something is in the public domain or not. A publisher can certai

That sounds like it is entirely the publisher’s internal policy, not at all related to whether something is in the public domain or not. A publisher can certainly impose their own restrictions before publishing something to lower liability, but that does not mean the photographs themselves are not public domain, as GP comment explicitly showed. If you have any case law since then that proves otherwise, great, but an anecdote is not proof enough.