Shoppers hate out-of-stocks. Period.
First, they drive to the nearest store. They park, walk inside and proceed to search for where that item should be. If they can’t find it, they might ask an associate for help – or they might leave and repeat the pattern at the next store. But when they do find where that item is supposed to reside and they find that shelf, hook, or peg empty… well. That’s a lot of time and effort wasted. And money, too, with the cost of gas today.