I should generalize the argument with more nuance. Not that a "photo" must have "people".
More accurately an "album" must have "living things". So a collection of photos must contain photos (not all) that have some living thing in it. There are some cases where this rule of thumb doesn't apply but, in general, a good album follows this rule.
More accurately an "album" must have "living things". So a collection of photos must contain photos (not all) that have some living thing in it. There are some cases where this rule of thumb doesn't apply but, in general, a good album follows this rule.