It's under agreement that on the web Google has one of the best ROI's for the marketer because intent is so clear in search. Few other people have the scale of Google to identically replicate that business model but I was curious why Apple doesn't try. Obviously there search has the same purchase intent, probably greater seeing as everything in the store is a way to derive income.

Is it for purity of the App Store? To not anger developers? Is it because the App Store is just a means for people to buy the hardware product so they want to deliver the best apps not the best funded ones?

I'm curious as to the reason why thats never been attempted seeing as implementing a promoted or adwords type product could be very lucrative for them, especially on iPad devices that possess greater real estate.