Most music librarians are saints: knowledgeable, hard-working, not paid enough.
But a few regard their employer's sheet music collection – much of which may be public domain – as their private property, and view those seeking to copy it as dangerous subversives who should be blacklisted from libraries across the known universe.
The notion that all printed music is protected by magic super-copyright may be a reaction to unlawful photocopying of music by students in the past. But that's no excuse for a professional librarian, trained in copyright law, to restrict the lawful copying of public domain music.
A similar point can be made about some music examination boards who enforce a 'no playing from photocopies without written permission from the publisher' rule upon examinees.
If the music is copied from a public domain source there is no good reason why it can't be used in an examination, with or without the publisher's consent. It's absurd to insist that an impecunious student should spend money on public domain sheet music which is available for free, legal download.
Far better for the money to be spent on copyrighted music so a portion of it goes to a living composer, and to a publishing house brave enough to publish his or her music, as opposed to one which churns out public domain reprints.
If you've had experience of 'music copying paranoia' share it here! Over-protective librarians, and others, can be referred to this post and encouraged to enforce actual copyright law as opposed to a fantasy which seems designed to stuff money into music publishers' pockets.