@munin I've watched enough USCSB videos and read enough NTSB reports to know that "complacency is a killer" so it's quite intuitive to me as well: if it works fine 90% of the time and doesn't
obviously fail for the 10%, you
will eventually get complacent and stop or half-ass checking it enough to "fall for" the 10% at some point. It's just human nature. There's a reason that pilots have strict checklists to follow, with Every. Single. Step. written down on them, and
even still there's the occasional incident because the checklist wasn't followed.