Why do we not get fired when we deliver poor quality?

I have just read the following post: There is too much money to be made in software development and I started thinking... I have heard about painters who were fired for doing a lousy job. I have heard about carpenters, accountans and bar staff who have been fired for being lousy at their work. But after some 6 years in the software industry I haven't heard about _anyone_ involved in developing software who have been sacked merely for delivering low quality software... Why is this?

A: Are we as developers not able to define what's quality seen from a developer's perspective?
B: Do our superiours even know what we're doing - and hence does not know how to measure the quality of the software we produce?
C: Is this just proof to the fact that the users of our system do not care one bit and hence our superiours do not want to fire somebody on the basis that the quality of the software is poor - as long as the users are happy?

I don't know... What do you think?