Would human monitors work better than ContentID in this situation?
I think a hybrid sollution (computer identifies the content, and if it is not sure about it being public domain or not, a human is used to give the final verdict) is probably the best compromise. But I expect that YT is already doing this.
From my perspective, people are just too used tolerating the bad things of ContentId which in part is the result of bad legislation.
In this case I bet that no human would be able to make a confident call because of multiple jurisdictions. On Germany it's public domain but on France maybe it's still copyrighted so you need an international copyright law master degree to figure that out.