Western Union struggles to maintain a "premium" price now due to competition.
The actual take on an average transaction from USA to El Salvador is way lower because El Salvador uses USD. So the only way to make money is on the Fee. (no foreign exchange revenue)
If you send $50, yes the take is high because there is a bottom to the price. But the average sender sends $200..$300 and cost, as a percentage, drops rapidly with the amount sent.
Many people thought bitcoin would destroy the remittance industry 10 years ago. It did not. People need money they can spend not bits in an exchange. Solve that last mile like Kenya did and maybe...
I don't think bitcoin can handle the transaction volume for the global remittance industry on the person to person scale for "money in minutes" service. It's a better fit for bulk transfers to pay the agents in foreign countries.