When building a ridesharing app, the developers learned that focusing on customer value and outsourcing non-differentiated features such as authentication, notifications, and payments can help speed up development. They used Auth0 for authentication and authorization, Courier for automating notifications across multiple channels, and Sendgrid for sending emails. By integrating Auth0 with Courier's Invoke Automation API, the developers could automatically create user profiles and send welcome messages without writing additional code in their application. This integration allowed them to focus on building the core product and provided a scalable solution for handling user onboarding workflows.