Not all app stores are in the same cycle of growth at any given moment. Some app stores are still in their growth phase, and comparing them to the more mature apple app store is like comparing exploding Asian economies to western economies. Oranges and Apples. So to speak.
Sales aren't the only way to generate revenue in the android market as =X= points out.
Ads are a growing part of
the revenue equation. Free apps with ads potentially convert a percentage of would-be thieves into revenue generators. Arguably
an iron fist isn't the best way to deal with piracy. I've got a few ad-supported apps, and they're not so bad. There are ads on my TV, ads in my newspaper, ads on the radio, why not ads on my crossword puzzles?
Different developers will find opportunities on different platforms. No one should assume it's easy to be a dev on iOS just because a few have made it big. Nor is Android the first platform to have some growing pains.