There's also the concept of the "Drift into Failure", which I believe was coined by Sydney Dekker (https://www.amazon.com/Drift-into-Failure-Components-Underst...), where small compromises in operations eventually cause very important security and reliability protections to be eroded away.
i tend to think this is a strength of the Russian R7/Soyuz: the vast majority of the R7 launch family launches are uncrewed (and with a lower level of "mission assurance," i.e. less double-checking), therefore any systemic problems (i.e. due to "drift into failure," etc) are almost certainly going to be caught in an uncrewed launch first. Likewise, uncrewed Progress cargo spacecraft missions use a very similar platform as the Soyuz spacecraft, I think on the same line, so problems with the spacecraft can also be found on uncrewed missions.
Falcon 9 is planned to launch maybe twice a year crewed, compared to 20 or 30 uncrewed launches (including like 2 or 3 uncrewed Dragon launches), meaning any new systemic problems with the launch vehicle will almost certainly pop up in an uncrewed launch before they result in loss of crew. Shuttle ONLY launched uncrewed, therefore any systemic problem which resulted in a loss of vehicle necessarily resulted in loss-of-crew.
Yes, so in the F9 case, that only works well if NASA doesn't insist that the one crew launch per year doesn't use a super-unique rocket. Which appears to be something that the safety committee appreciates, but maybe not far enough.
> Shuttle ONLY launched uncrewed, therefore any systemic problem which resulted in a loss of vehicle necessarily resulted in loss-of-crew.
Don't you mean that shuttle only launched crewed? Either that or I think I do not have the same definition as you do for "uncrewed" -- I take it to mean that there is no crew on board?
