Processing payments generally involves a minimum per transaction fee that is often too large a percentage of the microtransaction product price itself to make

Processing payments generally involves a minimum per transaction fee that is often too large a percentage of the microtransaction product price itself to make it work. As mentioned by another user, Paypal has a relatively new microtransaction processing service that helps address this problem, though, so there is some progress, at least for microtransactions of a certain size.