Physical book lending doesn't involve making copies at all, so copyright law doesn't apply.
That said, some libraries do lend scans of materials and libraries copying materials on microfilm has been done for ages. Interlibrary loans are done frequently with copies. Hell, the Library of Congress does it.
That said, some libraries do lend scans of materials and libraries copying materials on microfilm has been done for ages. Interlibrary loans are done frequently with copies. Hell, the Library of Congress does it.