A topic not so often elaborated about the App Store is the effect of ranking. This post is only intended to emphasize this fact, and of course it is not sure that Apple could find a better solution. The funny thing is that the success of an app (at least in the short term) depends much more on its ranking than on its quality. The App Store has become such a big store that it is easy not to find the best app you are looking for, because no one will check all 50 or 100 results he will get. The page 1 effect (similar to being/not being on page 1 on Google Search results) is actually the main driver of the success of an app. To give an example, I am one of the developers of Virtual Metronome, which currently appears as 3rd result when you type metronome on the French App Store. We see big changes in our sales when the position of the app changes from 7 to 6 (appearing in results for iPhone apps in iTunes) or 6 to 5 (when searching apps from the iPhone, you see 5 results without scrolling). What makes it a funny experiment is that our situation on US app store is radically different. We just don't appear in any main results and our current position is rank 43.
As in many markets, this situation favors:
An economist would tell you that this is common sense and that this effect is linked to several points: