To what extent is the Galileo effect described in that episode really just a kind of survivorship bias? If you've eliminated all the failures that can be caused

To what extent is the Galileo effect described in that episode really just a kind of survivorship bias? If you've eliminated all the failures that can be caused by non-redundant systems with no failsafes, then the only remaining failures are those that can be caused by redundant systems with failures (or at least slipped through). The way to see whether those redundancies and failsafes are working is to see whether the overall failure rate is decreasing, not solely whether failures are being caused by those redundancies and failsafes.