You're right, to at least a significant extent, of course. On the other hand, you're addressing a narrow field of software development, and quality can be measured, created, and "proven" differently in other development circumstances. The example that sprang to mind while I was reading it is open source development.

Within (successful) open source software development projects, QA personnel vastly outnumber core developers — and yet, a great many QA personnel turn into patch developers, while core developers become in essence project managers for bug fixes. The model further diverges in how one can recognize quality: you can track the very public management of bug fixes and the development process, and even view the code. So can everyone else.

Ultimately, the difference is to a great extent the relative ease of measuring its quality.

I had more to say — profound, wise stuff, of course — but I got distracted by the fact that Edward Scissorhands is on TV, and I forgot what I was going to say.