About 10-15 years ago, I found myself in a situation several times when the Internet, after my order, reported that it was impossible to fulfill the order because the book was defective. Since this happened with books published several years ago, I suspect that the store puts the book on display until a situation arises where the book's print run is over and it is not in stock.
When I purchased books as an intermediary, there was a situation where I could get the book from the publisher, but its price was already increased (not the price on the price list). It is also possible that Teodora ordered 10 books, but there were only 3-5 books in stock.
In general, this is a typical situation for Russia. I don't know about the USA.
It is also possible that the books got wet during transportation or were caught in a natural disaster.