Recent literature has drawn attention to the various regulatory battles and flashpoints triggered by the entry of platform Transportation Network Companies such as Uber and Lyft into cities around the world. Drawing on original case study analysis of Uber in Buenos Aires and Greater Manchester, we explore the increasingly complex and dynamic nature of local regulatory responses to platforms, and how they evolve over time. We develop a three-fold analytical framework that illustrates the important interactions between the competencies of local regulatory actors, the power of different interest groups, and the legitimacy of institutional rules. Our findings suggest that balancing these three components is crucial to counteract the increasingly embedded nature of platforms within local transportation markets. Looking beyond platforms, limited enforcement capacities within the local state and weak mechanisms of collective voice remain significant obstacles to the articulation of decent minimum standards within local economies.