Copyright is a specific legal right granted to authors, with the (ostensible) intent of balancing the rights of authors against the rights of readers. Copying a bunch of bits is legal by default, but we specifically outlaw copying certain bits under certain specific conditions. Copyright is not unconditional, universal or perpetual. In the EU, there is an element of "use it or lose it" due to the Orphan Works Directive - if the copyright holder cannot be located, then national libraries have the right to digitise and distribute the orphan work.

In the digital age, there is a perfectly reasonable case to be made for some kind of "unavailability exception" to protect the rights of readers in poorly-served markets and prevent anti-competitive hoarding of copyrighted works.

https://en.wikipedia.org/wiki/Orphan_Works_Directive