Or would push Mexicans to use other means (Bitcoin, black market means, etc.) to transfer funds back to Mexico. A 10% tax would alter behavior, no doubt.
This argument makes no sense whatsoever. You know why Mexican nationals use Western Union? Because it is simple, easy, and most of all safe.
Do you think that these people would rather risk all of the money on a black market solution instead of knowing it will cost them an additional 10% through Western Union?
Even if they understood Bitcoin and how to transfer it, do you think that their family in Mexico would understand it and trust it?
No. It’s a ridiculous idea that Western Union would suddenly lose all of it’s business from Mexicans who trust it and know it.
It’s like the same claim that if gas goes much higher then Americans will drive less. There might be a slight modification of behavior, but it won’t be significant.
Black market means yes, bitcoins no. Too complicated for them.