During a live AMA session with Abhishek Parmar, the creator of Google Zanzibar and current VP at Airbnb, key insights were shared on building large-scale authorization systems, drawing from Zanzibar's development to centralize access control across Google's ecosystem. Originally developed for Google+ to manage fine-grained privacy, Zanzibar evolved into a scalable service for products like Google Docs and Google Cloud. Parmar highlighted challenges such as managing data consistency and the complexity of low-level configurations, suggesting simpler abstractions could have improved developer ergonomics. For teams considering centralizing authorization, he advised planning shared group structures and metadata governance early. He cautioned against building custom systems unless operating at a massive scale, due to hidden maintenance costs. As AI becomes more prevalent, the focus might shift from authorization to ensuring proper authentication of agents. Parmar emphasized simplicity in designing authorization systems to avoid overly complex policies and recommended exploring resources like the Authorization Academy for further guidance.