In mobile security research, one of the many challenges is the lack of trusted user interfaces (TUI). Currently, users are not able to reliably identify which screen content is genuine and which is potentially manipulated. The concepts of trusted displays and user interfaces, which offer a high confidence in the trustworthiness of screen contents, are not universally implemented on current consumer devices. In this paper, we systematically analyze the developments in the field of TUIs on mobile devices over seven years. We present a new taxonomy to define and categorize challenges and issues in current UI designs, with a focus on issues that negatively affect the security of the whole OS. In addition, we suggest directions where contributions in research could solve these issues.