I'm not saying no mistakes were made. Of course mistakes were made. It was my assumption that the typical "post-mortem" process of those crashes did happen.
One of the many things NASA does for the US which affects ordinary people who aren't ever going to the Moon, let alone Mars, is ASRS. https://asrs.arc.nasa.gov/ The purpose of ASRS is to report safety problems that weren't accidents yet. That's how you continue to improve safety when there are a tiny number of fatal accidents - by studying all the things which nearly went wrong. The pilot who nearly turned off his one remaining engine after losing one on a twinjet, the controller who nearly authorised a new pilot to fly straight into a mountain before checking the radar again.
Most safety culture can't aspire to that. In many cases maybe it would be overkill. Therac-25 not withstanding, most software engineers are not going to kill anybody through their incompetence, and we'd do well to even manage a Mortality and Morbidity conference culture (M&M is what medics do when patients unexpectedly die or have seriously negative outcomes, to try to prevent such things in future). Even most of aviation isn't that safe. General (the pilot isn't getting paid, they're doing it for fun or at least as their own choice) is very unsafe. Commercial (e.g. Crop dusting, News helicopter) is better but not great. However Scheduled aviation (you can just buy a ticket, like for a bus) had reached the point where ASRS was the key to likely further safety improvements, and yet somehow Boeing shipped the 737 MAX.
My father is a retired airline pilot and we loved talking about safety, how things can fail and how there is a culture of learning for everyones mistakes. I mostly remember the pilots replaying actual crash scenarios.
But you are absolutely right, ASRS and learning from almost-failures is also critical.
If the airline industry had kept that culture we wouldn't have had so many incidents with the Boeing 737 MAX.