As an extreme example: NASA has done a pretty good job of making software without bugs [1].

    Consider these stats : the last three versions of the program — each
    420,000 lines long — had just one error each. The last 11 versions
    of this software had a total of 17 errors. Commercial programs of
    equivalent complexity would have 5,000 errors.

[1] https://www.fastcompany.com/28121/they-write-right-stuff

I wouldn't be surprised if NASA had a different definition of "error" than a typical "bug" in commercial software. My video player plays every single mpeg/avi/mkv I through at it. Yet it has dozens if not hundreds of serious bugs. I just doubt those bugs fall under the NASA's definition of "error".

Keep going, why don't we all write software the way NASA does?

(Also, it's just an analogy. I think perfect hiring would be much harder than bug free software).

Because companies are interested in profit; not top-quality software.

Anyone who tells you differently is deluded or lying.

That's why it's an extreme example.

I don't know if it's possible for anyone to answer this question but: does any organisation have a hiring process that's 5000:1 better than the average equivalent, like NASA's 5000:1 software defect rate?