Since 2021, delivery riders in Taiwan have organised unions to improve working conditions. Taiwan’s institutional framework integrates social insurance with craft unions, linking state insurance systems to unionisation levels in a way that parallels the ‘Ghent effect’ in Nordic countries, where unemployment insurance funds act as recruitment channels and sustain high union density. By leveraging their intermediary role in the social insurance system, riders’ unions recruit members and expand their base. Drawing on three years of qualitative interviews, this article demonstrates riders’ motivations for union participation, echoing Ghent–type mechanisms. However, this trajectory reflects an instrumental orientation of unionism that limits deeper member commitment and makes large–scale collective action difficult. Instead, unions pursue ‘atypical industrial action,’ including short–term, high–visibility protests targeting public authorities. These actions rely on a small core of members while mobilising consumers, NGOs, and broader publics, fostering digitally mediated solidarity and contributing to the passage of the 2026 Platform Rider Protection Act (PRPA). Yet maintaining membership requires preserving riders’ self–employed status. Unions have supported legislation covering only the self–employed, compelling misclassified workers to adopt this status to access protection and remain dependent on union–based social insurance. While disadvantageous to workers, this sustains union strength, producing a double–edged effect.