They many well be a volunteer. Lots of libraries are indeed manned by volunteers. My mum is one, to start off with they had a qualified librarian come from the big library in the town to support and get them trained but now the village library is fully volunteers only. Without them it would be gone.
The books are the main part of the library but it’s more than that and a good library is an amazing community resource. Lots of people come in to use the computers or internet often for job hunting, people come to photocopy, people come for local information or to pass the time of day, somewhere quiet to work or somewhere safe to spend some time. Vulnerable people. Book clubs. Baby rhyme time. Tots tales. Somewhere for all ages. Not just books; audio books, newspapers, magazines, films, Braille, resources in other languages.
The volunteers need to know how to manage the books of course and help with book enquiries but they also need to know how to deal with the library book terminals, the computers, the photocopiers, work the till, deal with the general public and all manner of random enquiries, open the building, lock up the building. So when they are recruiting volunteers I think the enthusiasm and aptitude for those tasks would probably rate higher than their personal knowledge of books. As long as they can find out the information they don’t need to know it all.
I know those two and I’m sure my mum would as well. But that said I know how hard her and her volunteer colleagues work and I would feel a bit sad if they got an eye roll or a complaint for not knowing a book even if it was well known.
You don’t know what you don’t know right? No one knows everything.
Also one interaction isn’t enough to judge someone really. If every time you go in they can’t or won’t help then that’s not ok but one conversation people may not be at their sharpest for any number of reasons. I once asked somewhat what their name was and they said they didn’t know. Obviously they didn’t hear me properly. In these moments you get to choose whether to make someone feel like a right idiot or not.
Be kind. Support your libraries. Volunteers are generally lovely and much needed.