Yes, retail stores have inventory that they, generally, have to purchase and hold before the sale. This is a natural limitation on the amount and variety of goods they can offer.
By comparison, app stores don't have inventory. But they do have natural limitations. There's a cost to each sale, represented by the 15-30% fees the App Store charges, which is a translation of underlying fees that Apple pays to host and distribute applications, whether paid to credit card networks, engineers, cloud infrastructure providers, supporting services such as iCloud, etc. There is a per-unit cost to app store downloads; its just that most of it is paid on the purchase, download, and use of the application, not hosting.
Additionally, App Store search result rankings are absolutely a limited resource which very closely resembles aisle space in a retail store.
When thinking about this specific issue (which dates back over 16 months ago? and has been fixed? why are we talking about this?): I don't see a philosophical or legal problem with Apple doing this. I see a usability problem. Its just bad results that aren't delivering what customers expect or want.
