Don't forget that "trust" is also not binary.
You can trust some people with some things, but not with others: eg. I can trust my dog not to steal my car, but I can't trust him not to eat the piece of chicken I left on the table.
And then also, you can trust people to varying degrees: eg. in terms of violence, I trust that my brother will not kill me, but I don't trust that he won't punch me in arm just for the hell of it.
People say "Oh, you have to trust someone!" To which I reply, "To do what?"