That's why I don't buy cars made by FORD, GM, or Chrysler
If you bought one of the above and the gas gauge did not work, would that keep you from driving?

I'd never, Never, NEVER, find myself in that situation, because I don't even consider their products, thanks to their business ethics, or lack thereof.
a parable, didn't you see

So, it wouldn't bother you that one out of every thousand boards that you built had a processor that didn't execute, say, CJNE properly?
A strange example, a typical "undetected" failure would be something like a dead port pin. If there was an unused pin that was dead it would not bother me enough to worry about it especially since I would not know.
Were I to (have people to) rigorously test every part before using it, the cost would get me an "interview with the president"

So it wouldn't cause you any heartburn if that 1 in 1000 processors that didn't execute CJNE properly was in use in a system that didn't happen to use CJNE? Wouldn't you worry that this failure was, perhaps indicative of a greater flaw in that part
Sure it would worry me if I knew, but if the product works I would'nt know. re knowing see above.

If one in every 1000 parts is defective, and you happen to buy that one, ... and, in fact, you don't know it's defective at all, so you assume it works. That can lead to the waste of a lot of time.
I never make just one proto. When working in other places where one was the norm, I was always conscientous of possible part failure -- coming to think of it, is that not the same approach as "possible bad joint on the proto?. Of course I also do so when having 3 protos, but the test is simpler.

Erik