Bananas was printer troubleshooting for the zoo when somebody printed a qrcode and instead of it being black the people set the colour as brown which the printer respected because printers like to do what there told.
Professor also noticed that qr codes are not black but a grey ish sort of mixture even on airline boarding cards.
I wonder what is wrong with black* ? PDF designers sigh there is more black ink than colour ink, its got to be a conspiracy by the colour ink industry.
*racism ? -joke