Each individual chip will have its own 'proportions' of Cyan, Magenta, Yellow, Black.
They could easily screw up one particular chip or run of chips. Should have no impact on chips made before or after. In theory, chips could also change appearance mid-print, if they were not all run in one go, if someone changed a setting. It begs the question whether B&G employ any quality control though. Apart from the obvious missing colors, one $5 is missing the background altogether, like a layer of the file got hidden.

Those of you with color laser printers that take 4 cartridges may know that if your printer allows you to ignore the 'toner low' messages and keep printing until one color dies, you can get 'cartoon like' images - the missing color can often be part of the shadows etc that give a pic 'dimension'. Some printers will start to 'fade' a color as it runs out. My current one uses the last drop of a color okay before omitting that color completely.

Before someone jumps down my throat about why I came into this thread, I believe I was part of Gene's 'We'