Putting simple things behind a qrwall. I once went to a presentation and they had that qr code to scan to get the certificate, and I went there without my phone, so I got no certificate (I needed it for academic bureaucracy). restaurants with qr-only menus also come to mind. Oh, I also saw once a school with the timetables mural with just qrs and nothing else written, so if new students didn’t have a phone AND mobile internet, they couldn’t find by themselves where and when their classes took place