What am I missing here? There are a list of piano rolls that have been scanned but you can only download MIDI from before 1929. I mean, I understand copyright

What am I missing here? There are a list of piano rolls that have been scanned but you can only download MIDI from before 1929. I mean, I understand copyright and public domain law in the US, but what exactly is the point of a list of things you can't share?