Copying for "private study, scholarship, or research" specifically by libraries is permitted by §108 [1], while fair use is permitted by §107 [2]. These are separate concepts.
Libraries are not intended for photocopying of materials for all possible fair use cases; they're only intended for "private study, scholarship, or research" purposes.
So the sign correctly indicates what's allowed per library policy; it also correctly indicates you have additional rights per fair use policy and warns not to go beyond those.
(A good example is that a teacher can use a private/school photocopier to make 30 copies of material for classroom use according to fair use; but you're not allowed to use the library photocopier to make more than 1 copy of anything.)
Copying for "private study, scholarship, or research" specifically by libraries is permitted by §108 [1], while fair use is permitted by §107 [2]. These are separate concepts.
Libraries are not intended for photocopying of materials for all possible fair use cases; they're only intended for "private study, scholarship, or research" purposes.
So the sign correctly indicates what's allowed per library policy; it also correctly indicates you have additional rights per fair use policy and warns not to go beyond those.
(A good example is that a teacher can use a private/school photocopier to make 30 copies of material for classroom use according to fair use; but you're not allowed to use the library photocopier to make more than 1 copy of anything.)
[1] https://www.law.cornell.edu/uscode/text/17/108
[2] https://www.law.cornell.edu/uscode/text/17/107