Right, to the customer it doesn't matter (just like to the developer it doesn't need to matter either - it just means the work needs to be performed).
However, it matters greatly to other observers - if one person or team is highly out of the norm for rate of bugs, it might be indicative of other problems that need to be worked on (lack of testing, peer review, tasks being assigned beyond the working abilities etc.).
Just like the restaurant analogy - the expectation is that bugs shouldn't be happening to begin with, and when they do, it should be "our fault" to remedy them.
However, it matters greatly to other observers - if one person or team is highly out of the norm for rate of bugs, it might be indicative of other problems that need to be worked on (lack of testing, peer review, tasks being assigned beyond the working abilities etc.).
Just like the restaurant analogy - the expectation is that bugs shouldn't be happening to begin with, and when they do, it should be "our fault" to remedy them.