The way Zidisha markets its rates feels like a lot of services I see. It's how my phone bill, electric bill, almost all my bills work - hidden fees charged by everyone so you just assume you're going to be paying more than is quoted.
They're following the status quo, are probably not intending to be evil, and are surely feeling the pressure to be 10x better.
But I worked in the Philippines in college, and you want to know what would really blow their minds? Not screwing them over. Everybody else does that. 10x better is being honest. Given their alternatives, 25% isn't that bad. Initial adoption might be slow - they're so used to corruption and being bullshitted that they'll think it must be 25% plus something - but once word spreads that Zidisha is really just 25% and offers the most valuable commodity in places like this - honesty and transparency - it will blow up. And then you'll get more fraud, but that's challenge 2.0.