Bar & QR Codes suck for the blind.
A sigil we can't see to know is there, requiring the ability to aim a camera at accurately, visual confirmation that the scanning device has indeed scanned the code properly, on a device we can't see the screen of, all to do something we probably need a Sighted Minion for to complete anyway.
Bar codes & QR codes may be nice for you sighted folks, but they absolutely *suck arse* for those of us whom can't see them to interact with them in the first place.
*Sighs*