There are a lot of major myths in the tech media about why piracy happens. Most believe that just because it's easier to sideload apps to Android, that automatically makes piracy 10x worse than on iOS, or something like that. But the truth is, if all else was equal, piracy on Android wouldn't be much bigger, or at least the dev would be able to earn about as much money on Android as he does on iOS.
The dev behind the Gentlemen! game for Android tablets and iPads (you get to play with 2 players on the same screen, so tablets make a lot more sense), says that the vast majority of Android piracy happens in countries like China and Russia, where they may not even have access to the Google Play Store:
About 95% of the pirated copies are being installed in Russia and China (and of those, mostly China). We didn't even translate our Google Play store into Russian or Chinese, so it's almost certain that the pirates just found our app on localized pirate sites.
If you're interested, after three weeks those numbers are now 144 copies sold, 50,030 copies pirated. So, as you can tell the piracy rate has not really slowed down at all - if anything it has gotten even stronger!
A lot of people in China get very cheap "Android-based" phones from small local manufacturers that aren't even licensed by Google, therefore those phones won't have the Play Store, so they wouldn't be able to pay for apps even if they wanted to do it. So many of them get the apps from sites that collect all sorts of apps from free to paid, and those sites have a lot of users/visitors. That makes it very easy for a game to be downloaded tens of thousands of times, and artificially boost the "piracy number" for Android apps.
It can't be compared directly with iOS, because most people there can't afford an iPad or an iPhone there. The company sold only 144 copies on Android, and over 1,000 on iPad. So what made the difference then?
I believe there's another factor at play here - Google's reluctance to promote the tablet category heavily in the Play Store. Apple has a whole different store for iPad apps, and people can just look there for iPad apps. You can't really do that for Android apps and games, which means games that are specifically made to be played on larger screens like tablets, will be drowned by all the other smartphone apps and games.
Plus, let's not forget that on average, Android devs still make about 2x less money on games and other apps on Android, so Google still has a lot of work to do with the Play Store, not just for the discovery of tablet apps, but for the discovery of all the games and apps, and do whatever is necessary to help devs earn more.