The Android Market had this same problem in the early days. It was frustrating but pretty amusing how terrible Google, of all companies, was at getting search right in their app store.
Example: https://play.google.com/store/search?q=child+books&c=apps But I agree, Google Play's search can still be improved. Currently a search for GTA vice city [2] places the actual game in third place behind other related apps. These apps are The important thing to note is that both these apps have 100,000+ downloads while the game is <50,000 right now. So the number of downloads is given a higher weight than name (as it should be.) But the actual game should get a better rank than other things. As time goes on and more sites link to the game and more people download it, this will improve.
[1]: https://play.google.com/store/search?q=%22child+books%22&... [2]: https://play.google.com/store/search?q=gta+vice+city&c=a...
Looks like that's already changed in the last 3 hours. Now shows up in first place for me.
Third place is currently some ripoff scam app, which is another problem. (Is there any way to report clear ripoff/spam apps from the web storefront? Had to into Google Play to report "objectionable content", which was the closest I could find to a fraud report.)
It's the same reason simply owning 'thing.com' doesn't make it your rite to be ranked #1 in google for 'thing'.
On a side note, and this might titillate you; I am seeing serious cracks in Google's search skills as their other assets lack search or it is rather clunky. Now if Bing just didn't suck so bad, there might even be a challenger.