In broad circumstances, it turns out that simple traits of trustworthiness will dominate in an evolving population. With more complex individuals it becomes necessary to recognize members of a behavior group and incentives arise to signal that you are a member of the group. Trust between humans may arise from a perception of character in the person to be trusted. In other cases one might trust an institution that has manifest a clear business plan to deserve trust. I suppose that this is the original reason that banks built imposing buildings.
Some advertising is designed to induce trust.
Bonding agents can produce synthetic but useful trust arrangements. Some people are naturally inclined to trust authority whereas others are just as inclined to distrust it. Hierarchical Certificate Authorities appeal to those inclined to authority. Schemes such as PGP's trust web attract the others. Ellison gives independent reasons to doubt hierarchical schemes.