It's not the clients that are treated differently, it's the types of transactions. If you use debit or credit to send money, the transaction is in real time and the rate is set at the moment you hit enter. There is no future adjustment as the transaction is completed right then and there. When you send cash through WU shop in your country, they enter the amount and see the conversion rate. But this transaction is not finalized until you pick up cash on the other side - and that's where the final rate established.