Lago's founders chose Ruby on Rails for their core API due to their extensive experience with the framework, allowing for rapid development and shipping speed. Despite criticisms regarding its scalability, they assert that architectural and operational solutions have kept Rails effective, even as they process millions of API calls daily. Lago has incorporated Go and Rust for tasks where Rails is less suited, such as high I/O concurrency and CPU-bound jobs, demonstrating a pragmatic approach to technology that prioritizes efficient product delivery over following industry trends. While acknowledging Rails' limitations, such as performance and concurrency issues, they manage these challenges through disciplined practices and selective offloading. Hiring has not been a significant issue due to a sufficient pool of experienced Ruby engineers and the company's selective recruitment process. Lago maintains that if starting anew in 2025, they would still select Rails, emphasizing the importance of choosing a technology stack based on the team's strengths and the ability to deliver a quality product swiftly.