I don't really know why in-app microtransactions, and especially in-app currencies, like this are even allowed in apps targeted at children. The worst example I saw was when my son was playing a mobile game based on a TV show for pre-schoolers. The developers had added an entire in-app currency, complete with prompts to buy packs of it when you game over, to a game explicitly targeted at children who can't even speak yet. I considered it a £60 lesson in better screening which games I install, but I'm still pretty pissed at the whole thing years later.