[battani]

If your money transfer model includes gateways, then trust is involved. You have to trust the gateways (local banks or exchanges) to make the conversion.

The gateways on each end would also want to take a fee.

Add to that the (MASSIVE) cost of compliance globally, and the costs of the model described by Stripe may not be much better than that of existing services (TransferWise, Western Union, etc.).

It's just an absolutely mind-bogglingly large, long, and costly endeavor, and the end results may not be worth it.