Jaeger-LeCoultre

John-E-Mac
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It is a conflict of humans and machines, combined with company policy.

Humans are taught to trust the QC system, so if it gets to them later in the process, then it must be "good". By the time it gets to the polisher, they assume all the prior checks have deemed the part as "pass". Same for the assembler.

Vision systems have to be programmed to measure features and have defined tolerances (straightness, perpendicularity, parallelism, etc.). The "straightness" of that edge is probably not defined or measured in their QC system. They probably only measure if the correct amount of material is removed (min/max).

Perfection has a cost. Imperfection has a cost. Finding an acceptable balance is a must in order to ship product to generate revenue. I've witnessed QA shut down production only to be over-ruled and product shipped.

I wouldn't be surprised that this defect was discussed at JLC and determined to "pass". There is probably a commensurate CAR (Corrective Action Report) floating around JLC.

In the end, the buyer is the final QC inspector. Good eye!