What makes medical practice better? The fact that doctors have made a ton of fatal mistakes that has cost lives. And they learned from those mistakes. That's pretty much how it is for civil engineers, and particularly in this case, for structural engineers. If you think doctors and engineers know everything and can't make mistakes, you're thinking wrong. Doctors and engineers and other professionals are researching, discovering, and learning new things everyday.
Anyway, check out this list on bestonlineengineeringdegree.com of
the 10 worst high-rise building collapses in history. If in case the link stops working, you can try this Google-cached copy of the webpage: