I don't think the OP knows what a librarian does these days.
As someone has pointed out, a qualified librarian doesn't need to know about books, it's about cataloguing, keeping online resources up to date..basically everything apart from stacking shelves. Someone working in a library doesn't even have to check books in and out now.
Think of the potential questions someone in a library must get now :
" Do you have House of Sleep by Jonathan Coe "
" Do you have old maps of Yorkshire "
" Is the latest Stephen King book in yet "
All questions that you just look on the computer for. No interest or knowledge of books needed. Just the ability to work the libraries enquiry and reservations system.
They also need some IT Skills, for the customer PC's, need to know how the photocopier works etc..again, no book knowledge required.
I think the OP is thinking of an enthusiastic old school volunteer who is passionate about literature and that is why they are there.