The person who taught me far more about how to program than anyone else wasn't a programmer. He was the operations manager of an Electrical Generating Station. He had a non-nonsense approach to testing, and the power to pull it off, that worked wonders. We both wanted the same thing, a program that users would have little trouble understanding or using, and accurate data when the reports were done. As others have said, it worked because our incentives aligned quite well.

Once the program was complete, it was deployed widely, and I spent a few happy years travelling around the region to support it, usually when the accompanying hardware failed and needed to be diagnosed/replaced.