Would you pay extra for ultimate QC?

Actually, making cameras is not that much more predictable. Cameras are made from thousands of parts. Each of these parts is made to within tolerances. It is impossible to make all parts perfect. When you put a lot of parts together the tolerances can average each other out, or accumulate to make a unit that is way out of tolerance. This is why the cameras have an AF Fine-tune. There can be differences between the mount to sensor distance in different cameras, and their can differences between mount and optics in different lenses.

Maybe we should buy a bag of cameras and just use the best ones out of the bag.

--
Robin Casady
http://www.robincasady.com/Photo/index.html
"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts."
— Bertrand Russell