It's unauthorized distribution.

You don't get in trouble for copying a licensed work, you get in trouble for making it available to others without permission from the current rights holder (or more likely, their hired thugs or your ISP).

How would Fair Use and libraries work if copying alone were illegal?

> How would Fair Use and libraries work if copying alone were illegal?

Libraries pay content owners in virtually every country in the world.

Well Fair Use is specifically about copying limited parts. Public libraries? How are they copying things?

Libraries provide both a system and the materials for facilitating the reproduction of copyrighted works.

They also don't pay publishers or content creators every time a material is consumed, and they don't employ DRM to ensure that people aren't violating the licences of works that are being checked out. In fact, they don't keep records of people while inside the library, so a content creator can't control how their products are being used and by whom. There are surely some DMCA violations happening at any given moment.

Copyright is an exception to natural behavior.

Libraries do not reproduce anything. They buy original copies and lend them out. Renting is a perfectly valid business model, and in this case it's paid by taxes.

But just because it's easy to copy does not make it legal.