Why did the under construction Hard Rock Hotel collapse? You can argue details, sure, but the result is the same. Accidents are less likely to happen with tons of redundancy in protocol and tons of testing before the plan is put into action. Someone in the planning process, and or building process missed a step or two or simply cut corners to save money.
https://www.cbsnews.com/video/2-killed-i...-collapse/
https://www.cbsnews.com/video/2-killed-i...-collapse/