Thanks for the long response, but it seems sort of far afield and I still feel my question was unanswered. MoneyGram reduces transactions costs by pooling wire

Thanks for the long response, but it seems sort of far afield and I still feel my question was unanswered. MoneyGram reduces transactions costs by pooling wire transfers to Mexico. So they take risk and add value as an aggregator. What's to keep a micropayment aggregator from doing the same?