I suspect that the cameras on low-end phones would struggle with OCR text in suboptimal conditions (low-light or damaged text). QR codes have redundancy, which

I suspect that the cameras on low-end phones would struggle with OCR text in suboptimal conditions (low-light or damaged text). QR codes have redundancy, which makes them resilient in a variety of conditions that plaintext isn't. Also, you can 'hide' ugly tracking urls in QR codes (e.g. a short-link that lets you count number of scans or update the redirect location).