Trusting people are prone to false positives, in thinking that some specific Other can be trusted.
Fearful people are prone to false negatives, in thinking that some specific Other can not be trusted.
The bias of our sociobiology is to be too fearful, just in case; it takes a high degree of civilization to nurture people who are too trusting.
Nonetheless, civilization is a great thing, the highest achievement of human beings. A bias toward trust is a good thing. And the best way to create trust in others is to be trustworthy, and to be trusting.