I don't think you could have made this point any better.
That said, I'm not calling for the abolition of either public libraries or little free libraries. I'm just saying we need to be clear about our goals when we do things (especially social justice things). If the goal is "put more books in the hands of poor kids" as an act of personal charity, then there are better ways to do it. Hence the example of my spouse.
There's a lot of intellectual dishonesty in the virtue-signaling claims of those in the article. It's not the virtue signaling itself that's the problem, it's being dishonest about the motivations of others for selfish aims.
Why do people put up LFLs? To share something they love. To decorate their yards. As a statement of culture for themselves and their neighborhood. Dismissing it as "virtue signaling" is deliberately derogatory. And this sort of argument is rife in the social justice movement in general. As someone who wears the "social justice warrior" label proudly, I'm not fond of the warriors who prefer circular firing squads.
It's hit-and-miss, though. I see no rhyme and reason in which books they're interested in, and the prices.
Just the day before yesterday I took some cooking books in pristine condition to the library. They used to have a book-swapping box outside. It was gone.
I went in (not too thrilled with the prospect of lugging it all back home) and asked about it. No, they don't have it anymore. I can put my books in the "free section" inside.
I did that, the librarian walked by to take a look and snatched the books away. "They are good, I'll see whether we can use them for the library. Usually we only get books we throw away immediately."
By "getting ride of it" I assume you put it into a glass case on your office wall. I admit it does deserve such a place of pride.
I don't think this is a good benchmark at all. It's a natural human tendency to think that we each are representative of "most people", but that's very often not actually true.
I prefer to donate unwanted books to the library, thrift shop, or used book store. Those organizations are in a better place to judge what most people want and what they don't.
Lisp in Small Pieces. Sure, here on HN many people would be interested in it. In a smallish town, even though there's a technical branch of a nearby university? Forget about it.
English books? The library isn't interested (for good reason, they have limited shelf-space and very little demand for English books, there are two shelfs of English fiction and that's it).
And even university libraries. I once asked them to buy Compiling with Continuations by Apple. A real classic. No, they won't. Too old, they won't spend money on that. Especially since it's available in several libraries throughout Germany. I am certain they would have zero interest in most of the computer science and programming books on my shelf.
Through it, you can borrow books from any library that is part of the system, which is almost all of them -- so even very specialized or obscure books that your local library won't carry can be ordered through them for borrowing.
Carnegie Mellon teaches a compiler course using continuations so I'm not sure what's "old" about it.
Originally an obscure descriptor confined to anthropology, it entered the mainstream via its use by self-righteous political and social commentators as a way of denigrating the thoughts, words, and/or actions of anyone whose opinions ran counter to their own.
By some of its many, constantly shifting, definitions using the phrase is an example of the phrase itself.
People who use it should be treated with the same level of incredulity that someone who uses the phrase "genetic terminator" when discussing vaccines deserves.
My own gripe against them isn't the virtue signaling, but rather the KonMari problem. People who read tend to treat books as sacred. Throwing books out is a sin, even if the books are, frankly, junk. I live in one of those neighborhoods they describe, with a little free library or two on every block, and they are often stuffed with garbage books that someone couldn't bear to throw out - old Danielle Steele and Steven King novels, obsolete computer books, etc. It's okay to throw books out, it really is. The magic isn't in the book, it's in the reading.
That said, there are other ways to do Good Work with books besides little free libraries and the public library system. My spouse works with a nonprofit that distributes books for underprivileged children. Every time she buys something on Amazon, she also buys a children's book - exclusively books that feature non-white characters. Her goal isn't just to get books in the hands of poor children, but to get minority kids images that look like themselves, and get the white kids images that look like someone else.