Comment by lxgr

> Bharat QR (India), Alipay & WeChat Pay (China) and QRIS (Indonesia) all support pre-auth and are widely accepted for hotels and car rentals in their respective markets.

Interesting, I didn’t know that!

Anyway, all requirements I mentioned definitely all feasible using QR codes (and apparently it’s already been done) – I just don’t think it would be a drop-in replacement at the terminal-to-POS interface if the existing terminal expects a credit/debit card like interface.

And the point you mentioned probably makes this a non-issue in many cases anyway:

> In many cases in these markets, merchants and consumers both went from dealing mostly with cash to dealing mostly with QR, so there is less of a legacy issue.