I disagree. It means trust but don't rely entirely on trust when you have other means at your disposal.
Consider a business deal. You take the contract to your lawyer and he puts all kinds of CYA stuff that supposedly protects you against bad faith. But let me tell you: if the other guy is dealing in bad faith you're going to regret getting mixed up with him, even if you've got the best lawyer in the world working on the contract. So you should only do critical deals with parties you trust.
But if the deal is critical, you should still bring the lawyer in. Why? Because situtations change. Ownership and management change. Stuff can look different when stuff doesn't go the way everyone hoped. People can act differently under pressure. Other people working at the other company might not be as trustworthy as the folks sitting across the table from you. All kinds of reasons.
So you trust, but verify that the other party can't stab you in the back, because neither method is 100% effective. It's common sense in business, and people usually don't take it personally. When they *do*, then that's kind of fishy in my opinion.