* «We have 100 widgets in inventory», you have one file copy,
* «a publisher prints 60,000 copies (instead of 80,000)», you still have only one file copy,
* «this book is out of print», files do not go "out of print",
* «dispose of inventory -- i.e., pulp it --», physical books have another counterpart: they are paper that can be sold, this has no parallel for electronic books,
* «competition for rack space», there is no rack space to compete for (there is competition for attention, that that is the same for every sellable thing).