Trust inherently depends on assessing others' interests [causal]
In contrast with the case of altruism, however, it does not make sense to cut trust free of mooring in expectations and hence, at least potentially, in interests. We cannot cut it free because our expectations will be grounded in factual assessments of the motivations of anyone we might trust. Among the most important of these must commonly be interests.
Russell Hardin, Trust and Trustworthiness, loc. 382