Literature on street vending regulation often emphasizes the challenges in enforcing legal frameworks due to unclear laws or insufficient state capacity. However, it tends to overlook diversity among vendors themselves along crucial parameters such as spatial location, community ties and processes of goods procurement. This diversity influences regulatory approaches, and understanding these differences can provide insights into broader issues of legitimacy and compliance. In this article, I trace the implementation of a street vending ordinance to examine the misalignment between legal instruments and everyday activities, drawing on in-depth interviews with vendors, community organizations and local officials (i.e. district supervisors, public works officials and police officers) in San Francisco, California. I use a case study in the Mission District to examine how, even in a context of strong state capacity, heterogeneity among vendors fundamentally shapes enforcement patterns and spatial outcomes. My findings reveal a paradoxical governance pattern whereby regulations disproportionately target those willing to comply with legal requirements while failing to effectively govern those actively skirting the law. This selective enforcement produces what I call a ‘legitimacy trap’ in which differentiated geographies of tolerance and prohibition emerge across urban space, reinforcing broader socio-political inequalities, producing unintended consequences and ultimately ensnaring compliant vendors.