Oh... I think this is ultimately just faith. You put faith, or trust into a person, and hope they do the right thing. I usually subscribe to the "Trust but verify" way of thinking.
And if they did not do what they promised, I just do it myself, or ask someone else to help, etc...
I think also this could be "forgiveness" based, but instead of a micro/individual level, it is more of a "humanity" level. Humans aren't perfect, and they will at some point disappoint you. Forgive them and move on, and continue to put faith on us doing the right thing... not all of humanity is untrustworthy. Call it being an "optimistic realist".
Hope for the best, see the best in people, but also realize that sometimes people will fail you, or be less than optimal. It's part of why life is so exciting... drama is ultimately interesting... if not for you, the people watching it...