The major problem for large publishers is that they are not certain what they actually own. If you would like to amuse yourself, pick an out-of-print book from the library and try to determine who owns its copyright. It's not easy. There is no list of copyrighted works. The Library of Congress does not have a catalog. The publishers don't have an exhaustive list, not even of their own imprints (though they say they are working on it).

It is so good, in fact, that we can now state a new covenant: Copyrights must be counterbalanced by copyduties. In exchange for public protection of a work's copies (what we call copyright), a creator has an obligation to allow that work to be searched.