"Catastrophe requires multiple failures – single point failures are not enough." I disagree with this point. From what I have seen and experienced, there are s

"Catastrophe requires multiple failures – single point failures are not enough." I disagree with this point. From what I have seen and experienced, there are so many SPOFs in the real-world complex systems that do not have adequate defense or even any defense at all. The only reason catastrophe didn't occur (often) is only because the natural failure rate is extremely low. Like the probability of air traffic controller making a critical mistake is very low, maybe once every few years, but when it happens, the SPOF will almost certainly cause a disaster, and the system (ie. the way air traffic is controlled today) has been around for decades and is so outdated but the cost of changing the entire process around the world is simply way too high so we just take this as "normal".