There could be cultural factors at play here as well. When I was growing up in Turkey, every so often there would be a fad that picked obscure artefacts of American culture and turned them into articles of social prestige. Cheesy American soap operas, songs and actors would suddenly and inexplicably become national sensations that everyone had to know. I assume something similar is going on with the Android Play Store reviews. Having your review on the frontpage of an app had become a point of pride, so much so that users are subverting the system to get there.