When the cost of the electronics is a tiny fraction of the overall product the equation is different. Automotive is a perfect example where spending extra on a few key components is a worthwhile investment if that can increase the reliability of the entire vehicle.

Actually, 1000dppm (99.9% defective parts per million) is not acceptable except for hobbyists. Typical commercial manufacturing requires <100dpppm due to the number of components and cost of returns. This can be met quite reasonably with statistical sampling and process controls. Every single IC gets tested, it's just a question of how thoroughly and whether the control limits are set well. You need to do R&R studies, but the infrastructure/procedures are usually available to approach 6sigma (even if it's a bit hokey).

Where this is going a bit nuts is that that it's hard to make 100 gold contacts last for 1000 compression cycles at 1 dppm (better than 6 sigma!). That requires a lot of excess maintenance on the test infrastructure! That will be expensive... and your assembly connectors/SMT is likely orders of magnitude higher defect rate than 10dppb so it won't improve final assembly performance.

Also, I think you need another 9 on that 99.99999% to hit 10ppb and realistically 2, if you want to have an acceptable yield rate, and 3 on the test equipment since they are used 10k times every day.

If the unit that has to be replaced is large enough, as it is for cars, it pays to get the component reliability up. Failure of IC can mean replacement of dashboard or power train.

Not-working parts are out of spec (kind of by definition).

If I buy a part, I'm paying for a working part.

If I buy a million parts, I'm probably paying for an acceptable (to me) failure rate, which is probably negotiated as part of the contract. He who buys cheap, buys a higher failure rate.