They very likely have all of these protections in place, and more. Large-scale outages of mature systems are almost always a cascade of small human errors that,

They very likely have all of these protections in place, and more. Large-scale outages of mature systems are almost always a cascade of small human errors that, each on their own, would have caused negligible damage. It's only when they happen to align with each other that a large disaster is realized.