Also all the sites that post scans of old books or magazines but claim various usage restrictions or/and copyrights on the scans.

That effectively keeps public domain works copyrighted, for most purposes, for most of us. Most libraries for instance have some EULA that says you can only use scans you order from them for non-commercial purposes, even if they scan from a public domain book. I do not know if that can be enforced in general, but it would not be fun to have to find out in court.