Write a literature review about 3,000 words on the topic Implementation of Electronic Tax System: A Developing Nations Perspective. Discuss the benefits and challenges faced in developing countries. Also, provide recent developments in this area. Conduct a comparative analysis of at least 4 developing countries and developed countries. Additionally, provide information on Fiji and its legislations regarding such systems, like TPOS. Use credible sources such as journal articles and credible websites with proper referencing.