What's Going On Here: Android is the largest smartphone platform by units sold, but has traditionally trailed iOS in terms of app quantity and quality. The last year has, in my experience, closed the gap a lot. There are few apps you can't find on Android, and quality discrepancy — at least on newer phones with up-to-date versions of Android — is far less obvious.
The ecosystem is still a little strange, in part because of the Android Market's strong free-over-paid culture. The free apps column is full of familiar names and marquee brands; a rough survey of the most important apps on any smartphone platform. The free games, however, are mostly either Android native or relatively obscure.
The paid apps selection is distinctly Android. There are some games, but also an array of power user utilities: alternative homescreen widgets, and alternative keyboard, a file manager. One, a backup tool, makes the list despite requiring users to have rooted their handsets. The people paying for apps on Android are its most dedicated users, and the kind of people who like to tinker.
It's most popular paid apps don't only not exist on other platforms — they often couldn't.