6.1.2 Social norms
Social norms dictate that we don't light a cigarette in someone else's house without asking permission. When I first came to the south of England to work, I didn't know I was not supposed to say hello to a stranger on a train. I was subject to suitably disdainful and horrified looks from my fellow passengers, who tried valiantly to ignore me. Having been normalised after 20 years, I can dish out the dirty looks with the best of them.
Social norms, like the law, punish deviation after the event.