Scaling retail is hard. Especially if you're against "be on call 24/7 for minimum wage without additional on call compensation".
They could buy self-checkout terminals, though, but I imagine they don't want assets like that and would rather let the business fail. That's the writing on the wall (if not the stock trend)
Especially in December - during prime holiday shopping hours - you staff up. It's more profitable to have a little bit of employee slack time than to have customer satisfaction way down and customers walking out without buying things.
This is a bad take - the whole "oh retail will die without self-checkout terminals" overlooks the realities of retail, what consumers want when they choose to go into an actual brick and mortar store, and how businesses can succeed. And it does so in a way that perpetuates the implication that we have to treat employees like computers to be successful.
For big box stores, but B&N are on the decline, while real estate and lease prices have likely risen.
"you staff up" works when you can actually pay for the excess, but B&N clearly don't want to. But you missed the point of my take in that they aren't willing to invest in assets for customer satisfaction. They're on the way out, so why would they care to staff up for holidays either?