Not necessarily. For instance, if you wanted to self-publish, you could spend money by contacting a local press and asking them for their print run costs. Maybe you want 5,000 copies of your book and you're going to sell them at fairs and whatnot. That would not be POD (Print on Demand). With POD there are no physical books sitting in a warehouse anywhere, the books are printed one at a time when they are ordered. That doesn't mean you can only order one book, but the machine only makes one book at a time and it makes a complete book, then another book would be printed. The costs are higher per book.
It is very possible that a small press might make a print run of 1,000 copies of a book (or some other number) if they have a place to store them, have distribution, have a marketing strategy for said books, etc. They also might use POD by using Lightning Source. When an order is placed, they contact Lightning Source to fill the order for them and ship it out. The publisher would never actually see the copy of the book.