I understand the anger but bottom line is workers will make mistakes and machines will break.
100%. Quality checks and human error will only ever be as good as the control plan that's provided.
A decade ago I was on the production floor at a Tier 1 doing metal stamping on night shift. One day I got asked to stay late in the morning to see my Manager, where he confirmed what parts I had run the day before. He indicated that 4 bins (let's say at least 4,000pcs) were defective due to hairline cracks in one of the corners. I asked him to show me the hairline crack and he handed me a part and a flashlight, yep, i could see the crack. He went through a checklist with me;
1) Did you not notice the cracks? No
2) Did you follow QA and check first/last off and every hour? Yes
3) Did you follow the control plan? Yes
4) Did you make appropriate notes during your run? Yes
Then he told me, because 4,000pcs had to be scrapped I was going to be given a written warning and slid it across to me. I read it over and refused to sign it. He was just sitting there with his mouth open, clearly the last thing he expected me to say. When he asked why I wasn't going to sign it I said "Show me on the control plan where I'm provided a flash light to check the corner of the parts." (It didn't exist). He got upset and told me to get lost. Never heard another word about it, lol.
Obviously the control plan called for visual inspection. However this hairline crack was impossible to see without the aid of a flashlight.