In app purchases are a scam, pure and simple, and need to be outlawed.
A few days ago, my six year old son brought his android pad to me with a problem he didn't understand. It turned out that the car game he was playing was trying to take a payment of 79 quid for a new paint job or something. Fortunately my card details have never been, and never will be, entered into the system. There is absolutely no excuse for that kind of functionality in a game targeted at young children.