Public transportation services had constantly developed and expanded in accordance with the population growth in South Korea. Nonetheless, various issues such as an increase in government subsidies and the deterioration in the quality of public transportation services have recently been occurring. These issues stem from drastic rural depopulation, urbanization, and low fertility rates. Even though local governments agonize over confronting issues by improving their management systems, there are fundamental constraints to solving issues. In response to these situations, recent advances in platform technology in the mobility sector have led to a great stride in DRT (demand-responsive transport) platform services. The app-based DRT service looks forward to improving the quality of public transport services and bringing out significant solutions to existing issues. There have, however, been trials and errors in the case studies that DRT services are implemented without sufficient pre-analysis and simulations. These cases have mostly encountered obstacles when setting up oversaturated service areas and fleet deployment, adequate by-pass ratio, and securing the punctuality of services. The study synthetically classifies DRT services into three operational levels according to the sense of the booking methods, operation method, and pre-planning levels: DRT 1.0, DRT 2.0, and DRT 3.0. Besides, it conducted an in-depth analysis of the pros and cons of each operational level. The study ultimately authenticates the operational excellence of DRT 3.0 by comparing the key performance indicators and operational efficiency in the case study of Cheongju-Call-Bus, based on the advanced planning method of DRT 3.0.