What Xoom is doing is not generating any sort of expense to the country nor doing anything to Inflation. The problem is money leaving (ARS to USD), not money coming.(USD to ARS).
Well, it is an expense because those dollars that are being sent through Xoom never end up in the country. If they had been removed from an ATM, they would have wound up in the Central Bank's account at the NY Fed.
More pays this rate because it's competitive, and it's the only way to stay in business. It really makes no difference to them what the rate is because they're just making a "spread" of sorts.
And if you look the transfer receipt, nothing about dollars is ever mentioned. I'd assume that the receipt they have you sign is the main document that is reviewed by the AFIP, UIF, etc. There isn't an exchange rate. There isn't the dollar amount. It just says that someone sent you X-amount in pesos.
Infobae reported a few months ago that they'd soon start regulating these folks. Evidently, in order to mask the exchange rate, places like More are tacking on high commissions:
En el caso de las remesadoras, por ejemplo, existen varios cuestionamientos por las comisiones que cobran a los clientes. En algunos casos, representan la mitad del importe máximo permitido para girar al exterior.
This seems to be the loophole. Let Xoom calculate the rate to avoid responsibility, and then tack on high commissions for those who send money in order to compensate.
It's not their fault, though. How else would they get the dollars to stay in business?
Vamos por más!