Look up 17 usc 108.

https://uscode.house.gov/view.xhtml?req=granuleid:USC-prelim...

What's with the goalpost moving? Click on "Final Rule"[1] and the PDF goes into copious detail about what exemptions are currently in effect. Obviously there is no, and will never be, "carte blanche to libraries, however they care to define themselves, to have any generalized exemption from copyright law". There are specific, temporary, limited exemptions in effect.

[1] https://www.govinfo.gov/content/pkg/FR-2024-10-28/pdf/2024-2...