Yeah, that would be why we don't shop there, either you pre-order it, or they typically don't have it.
It's just how they operate. If a lot of people preordered something, there's an assumption of a lot of people buying it down the road as well, therefore they order more copies than they need. If noone preordered it, noone's going to want it later on either. Considering how long the PC stuff hangs around on the shelves here without selling, I'm not surprised it's gone down the tubes elsewhere.
It saves them from wasting inventory space, for the most part.
On a lightly related note I laughed when I saw the gigantic box full of Gears of War 3 copies when I picked mine up...hee