I am a huge library supporter, both with time and $$. I serve on two library boards. In normal times, I help run five large book sales (5-6,000 curated items each sale).
I agree that the "savings" is false an illusion, in the same way it is at the grocery store. We pay for libraries via our taxes. Most importantly, as Mustachians, absent library access, we would find other ways to source books than paying retail for them.
Example: I volunteer at a Thrift shop. On Tuesdays, every book is a quarter. It wouldn't be nearly as impressive to say I bought three books for seventy five cents. Plus, I would own them, so there would be no possibility of the dreaded library fines.
I think posting the "savings" is gimmicky. It also feels calculated, as if patrons are being reminded how much they should appreciate what the library is doing for them. Apologies to all the underpaid/overworked/underappreciated Librarians out there, but y'all know where the money comes from.
Currently, our libraries have no limits on checked items, and no fines for "late" materials. My friend has library cards in two different systems (legitimately). She always has a large number of requests working. During the pandemic, all of her holds started coming in, so she has averaged over a hundred items checked out at once. Imagine what her total "savings" would be. She must be rich! Which is exactly what I say, every time a grocery person tells me how much I've "saved". Especially on Senior Morning, lol.