It's also completely untrue that the norm outside of software engineering, I think this perception comes because we only think of the big engineering projects like NASA or building projects, and forget how broad engineering is and can be. I worked for a company that mainly did electrical engineering, and there was plenty of happy-path work that just assumed the error cases would happen rarely or be handled somewhere else. It was also quite difficult to get good change control working, and automated testing was painful and irregular. (In fairness, automated testing was also a lot harder, but we could have worked harder on it and caught a lot more issues early on.)

My impression from friends working in other engineering disciplines is that software engineering works similarly to other fields: the more risk to human lives is involved, the more testing, redundancy, etc is involved.