It's not the painting at issue, it's the reproduction. Photographs of paintings have copyrights that belong to the photographer. If you have access the the old painting and take a picture of it, you control the copyright of that reproduction.
I think the confusion here stems from the fact that that statement assumes you don't have access to the painting, which is the most common case.
I think the confusion here stems from the fact that that statement assumes you don't have access to the painting, which is the most common case.