If you're talking about piracy, do you only read books from dead authors? Or do you pay them via alternate channels? Or are you just fine with enjoying their content without paying them back a cent?

If we're talking about used bookstores, the author makes just as much on a pirated book as a book purchased at a used bookstore.

...we’re talking about public libraries.

If we were, we would also be talking about a way to read books that the author doesn't make a dime on.

The cost of lending and reselling a book is explicitly part of the initial remuneration.

Books deteriorate, and a normal book can only be lent or resold so often. A paperback read by one reader is usually in a good condition (but obviously 'read'), a paperback read by twenty readers (who took it along on travels, dropped it, put it on dirty surfaces, etc.) will be near the end of its life. Hard-cover library books can take more of a beating, but are read by more people and get damaged nonetheless. The average lifespan of a popular library book is short.

If books didn't deteriorate authors and publishers wouldn't make any money from second-hand or library books, but as it is, they do. Any time you read a book, it gets closer to being taken out of circulation. Any time you purchase a book and keep it, you take it out of circulation for years, decades even. That all drives the need for new editions of that book. This is no different from second-hand cars or bicycles.

If it's obscure, it's certainly not readily available on torrents (or in local libraries) if that's what you're suggesting.