This paper delves into the pressing issue of securing affordable housing in global cities amid tourism-driven gentrification. Short-term rentals (STR) via platforms like Airbnb threaten housing availability and affordability for permanent residents and long-term tenants. To better understand the complexity of improving effective regulations for STR (and for mid-term rentals as well) and of the role played by political and socioeconomic actors in either strengthening or watering down regulations, the paper dissects how legal regulations and local policies shape housing dynamics and the expansion of STR in Buenos Aires and Barcelona, two gentrification and STR hotspots. The study shows that, despite varying regulations and governance approaches, both cities struggle to regulate STR effectively. We find that real estate actors are able not only to escape regulations through loopholes but also to accumulate more profit over time and rather quickly. It underscores the complex interplay of legal frameworks, mayoral political orientations, and uneven disputes between different stakeholders in the context of STR expansion and further highlights the need for robust legal frameworks, enforcement mechanisms, and multidimensional policies to ensure equitable housing rights for all.