One of those things you keep revisiting

When I was a software development manager, one of my annoying little ways was to draw my engineers' attention to the Therac-25 disaster, periodically. Therac-25 was an early and horrifying example of why you can't just let people hack software together without a process of some kind.

This happened back in the mid- to late-Eighties. Essentially, a Canadian company that made radiation therapy machines allowed all the control software to be developed by a single engineer. That person alone made decisions on code reuse, new development, and testing. In fact, he or she did most of the testing. The work was done in PDP-11 assembly language, running on a proprietary operating system. People died. The link above will give you the standard write-up on the problem, done by independent software engineering authorities.

It probably won't take thirty years for the launch of the Affordable Care Act infrastructure to become a standard and almost equally horrifying example of why extensive and elaborate processes aren't even remotely a guarantee of software quality, either.

I think I'm going to stop admitting that I worked in the industry at all. If anyone asks, I spent 33 years driving a garbage truck.