SAN FRANCISCO — When people enter Teeth, a bar in San Francisco’s Mission neighborhood, the bouncer gives them options. They can order food and drinks at the bar, he says, or they can order via a QR code.Each table at Teeth has a card emblazoned with the code, a pixelated black-and-white square. Customers simply scan it with their phone camera to open a website for the online menu. Then they can input their credit card information to pay, all without touching a paper menu or interacting with a server.A scene like this was a rarity 18 months ago, but …
