Food is where culture stops being abstract, and dining etiquette is packed with meaning that outsiders easily miss. How people eat encodes their values: cultures of shared plates express community, strict table manners express respect for order, waiting for elders to start reflects hierarchy, and rituals around serving guests express hospitality. Whether you finish your plate or leave a little, whether refusing seconds is polite or insulting, who pays and how hard the other person is expected to protest, all of it varies and all of it means something.
Getting this roughly right matters because meals are where relationships are actually built in most of the world. Business deals, friendships, and family approval all pass through the table. A guest who handles the local dining code gracefully signals respect for the whole culture, not just the food.