Is that “most” just weasel-wording, or is there actually some country out there whose laws don’t consider that country’s passports to be government property?
Interesting point. But even a United Nations Laissez-Passer “is the property of the United Nations” and “remains the property of the Organization until it is formally cancelled by one of the issuing offices”.
Norwegian passport legislation does not write that the passport is government property, but lists reasons the passport may be withdrawn and legal steps to be taken if the holder refuses to return it.