Trust is not one thing, and that's the most useful thing to know about it. The standard model in the research breaks trustworthiness into three parts: ability — can they do this; benevolence — do they have my interests in mind; and integrity — do they hold to principles I can predict. When someone says "I don't trust him," they almost always mean one of the three, and the three have completely different remedies. A competence gap needs training or a smaller task. A benevolence gap needs a conversation about interests. An integrity gap is the serious one, and it isn't fixed by either.
If you can check, it isn't trust. The definition in the literature turns on vulnerability: trust is the willingness to be exposed to someone else's choices without the ability to monitor or control what they do. That's uncomfortable, and it's the point. What most people call trust is a verification system with good manners. Real trust always costs something, because it always involves the possibility of being wrong.
It builds slowly and breaks fast, and there's a reason. A single failure carries far more weight in your assessment than a single success, and it's not irrational — one betrayal tells you more about a person than one delivery does. What follows from that is practical: you cannot recover trust at the speed you lost it, and the attempt to do so reads as pressure. What actually works is a long sequence of unremarkable, kept commitments, which is slow and boring and the only route there is.
Trust and liking are different. You can like someone enormously and not trust them with a deadline. You can dislike someone and trust them completely. Confusing the two is how organizations end up handing important work to the most personable person in the room, and how families end up unable to say that someone they love is unreliable.
That's what trust is — not a feeling about a person, but a decision to be exposed to them.