Isn't the saying "Trust, but verify"
Getting back on topic, that’s entirely Visa’s business in being a payments network. When I first heard about Bitcoin and cryptocurrencies, I wondered why Visa/MC/Amex/Discover and even (newer) real estate companies like Redfin weren’t looking at this seriously, since it could hypothetically be used to verify contracts and transactions in a decentralized way.
You don't need to trust people on a blockchain, you have to trust the protocol, and then verify the results.
"Trust, but verify" is Reagan's slogan.