The industry made a mistake in not using Data Matrix barcodes over QR. Data Matrix fixes most of QRs problems: illegible at small sizes (sizes one would have if displayed on a phone), poor contrast (won't read if your phone's display is at low brightness), and an overly complex design exacerbating the previous issues.
The only benefit of QR over Data Matrix is the capacity for larger file sizes and thus QR allows for higher error correction in the spec, which is seldom used.
