The rapid eye contact before totally ignoring someone is an urban thing. There are simply too many people. And the people who violate this norm are either reall

The rapid eye contact before totally ignoring someone is an urban thing. There are simply too many people. And the people who violate this norm are either really bad at social interaction, or they want something. Or they're lost and need help, which is fine! But even today, the rules are different in rural areas. If you live on a dirt road with a dozen houses, and you run into someone you don't recognize, it's pretty common to say hello, and maybe introduce yourself. The neighbor who never talks to anyone stands out. On a hiking trail, you nod, say, "Nice weather," and keep walking. The point is that every social environment has a "normal" behavior. People who pick up on that normal behavior probably understand the basic rules of society. People who ignore that behavior are less predictable, or are deliberately breaking the rules.