> I'm not sure the need for it follows from it being public domain?
There's something specific about the public domain that in many places, you can't just decide to release something in the public domain. I guess that's why they actually accept contribution but require an affidavit dedicating the contribution into the public domain. IIUC an affidavit specifically needs to be witnessed by taker of oaths, which probably ensures that the work can indeed be put in public domain.
Not sure it's the whole story, or even the main reason, or the correct analyze, though.
There's something specific about the public domain that in many places, you can't just decide to release something in the public domain. I guess that's why they actually accept contribution but require an affidavit dedicating the contribution into the public domain. IIUC an affidavit specifically needs to be witnessed by taker of oaths, which probably ensures that the work can indeed be put in public domain.
Not sure it's the whole story, or even the main reason, or the correct analyze, though.