I think part of this may come down to how we define "trust". Words are so tricky
I may have a friend who adores spicy food. If I let them choose a restaurant, and they choose something spicy, then I don't trust them going forward to choose restaurants I will find match my palate. It's not that I am judging them to be "bad" or wrong or anything. It is just that I know what they provide is not what I seek.
If someone plays piano badly, then that is fine! But I would not choose them for my wedding. I would not "trust" them to play for my wedding. Maybe they are an awesome cook and would make the very best cake known. But I wouldn't keep "trusting" them to play the piano at my events, hoping they would get better. Instead, I would go with someone I knew did play the piano well.
So if a person always lies, it does not help me or them to keep putting them in situations where they will fail and I will be upset. Instead, I accept that they tend to lie, that it is part of how they handle life. And I make sure I am not in a situation where their lies may cause serious problems. I would not have them be the executor of a will for example. I wouldn't trust them to do brain surgery either. Every one of us has our strengths and weaknesses, and it's wise to be aware of them, I think.