Did a self checkout recently at a store I'd never been to before. Went through pretty smooth, shoved receipt in my pocket, and then saw they had little security gates and a receipt scanner, so I had to fish out the crumpled paper from my pocket, fumble around trying to find the barcode thing, and of course it also had a random QR code that I tried to scan for like a minute until the security guard had to come over and help me. Luckily it wasn't that busy, but if there had been someone waiting behind me it woulda been a nightmare.