Knowledge and awareness of the relationship and trust between man and technology is important for users to accept artificial intelligence (AI) and autonomous systems. While research has been conducted on the interaction between operators or passengers and robotic vehicles, there is not much research on secondary users, i.e., users who are not directly interacting with the system, such as pedestrians or bystanders in the robot's environments. This paper summarizes and synthesizes the existing literature relevant to secondary users' trust toward autonomous systems. The focus is (1) to find out how the secondary user experience in human-robot interaction is affected by trust, and (2) to see how trust is designed in autonomous systems. By designing for appropriate levels of trust, the designer can empower both primary and secondary users to accept the information provided by the robot and follow its suggestions.