> I trust my doctor and my doctor trusts their sibling, but I don't necessarily trust their sibling.

Isn’t that because that’s a different type of trust? For example, you trust your doctor to give you decent medical advice, and they trust their sibling for emotional support. That doesn’t mean their sibling will be supportive of you, or give you good medical advice.

Yeah, this is one of the big issues with digital peer trust networks. Trust in human interactions is fuzzy and very conditional, which is hard to collect, represent, and update in a user friendly and low effort way. Hence we tend to collapse it to a single, often-binary, trust score.