I'm an Android user but recently I purchase an iPad and I really hate the iOS app store and this is why.
Pretend you purchase an app because the description, screenshot and reviews all look positive. After running the app you find it has bugs which make it mostly unsuitable for the purposes advertised, or maybe an advertised feature doesn't work quite the way you were expecting.
You can go to reportaproblem.apple.com and state that the "Item opens but doesn't function as expected" however you will then be told to go to iTunes Store Support or the app developer's site. It seems if you want a refund you need to write to Apple and even then, I'm not sure whether Apple facilitates refunds via this channel.
If you buy an app via the Google Play store and decide it doesn't work for you, you can simply uninstall it within 2 hours and be issues with a refund automatically, no questions asked.
If people know they can trial apps without financial commitment, I think most people would be willing to hit buy without as much hesitation compared to the iOS store where the refund process is elusive and time consuming. Some may say you could exploit a more lenient refund policy but how much value can you get from having an app installed for 2 hours anyway? (games may be a separate matter)
This happened to me once (and I now simply refuse to cough up any money in the iTunes store unless it's a well known app).
Apple support emails made it sound like they were doing me a huge favor by refunding my money.
It was only $2-something, but I was annoyed that the app was just a blantant lie and did absolutely nothing from its description in the App Store.
I experiment much more on my android apps from the Google Play Store knowing that I can refund it if it doesn't function as expected.