It could also be that the developers knew about the bug, reported it, were told not to fix it (probably due to more "important" work), and then either managemen

It could also be that the developers knew about the bug, reported it, were told not to fix it (probably due to more "important" work), and then either management or sales hid the bug from their customer and denied their software could be at fault. I.e. garden-variety lies to customers and management face-saving. The way developers can be at fault here is if they managed to conspire with QA or testing to hide the existence of the bug from their management and continue to deny it when asked. Which implies a pretty toxic workplace, but, then again, Japanese conglomerates are not famous for sunshine and daisies. And sure enough, that's the claim: https://www.computerweekly.com/news/252496560/Fujitsu-bosses-knew-about-Post-Office-Horizon-IT-flaws-says-insider https://www.computerweekly.com/news/252496560/Fujitsu-bosses...