I wonder how this type of 'small' issue with a 'big' effect gets past QA/QC. You'd think it would have failed during standard mechanical usage tests, but appare

I wonder how this type of 'small' issue with a 'big' effect gets past QA/QC. You'd think it would have failed during standard mechanical usage tests, but apparently it didn't, or didn't fail reliably? It's a stupid issue of course, but I'm more interested in how this type of thing isn't caught.