Because in many Vietnamese families, asking about food is how people ask about you. “Ăn cơm chưa?” — have you eaten rice yet? — often functions less as a question and more as a check-in: are you okay, are you taken care of, is anything wrong.
Vietnamese has plenty of ways to say "I love you" and "I miss you," but in a lot of households those sentences are used sparingly, especially between generations. Care tends to be expressed through action: cooking, feeding, cutting fruit, packing leftovers, keeping the rice cooker full.
"Ăn cơm chưa?" sits right at the center of that. It is a greeting, a wellness check, and an offer all at once. Answering "not yet" frequently triggers immediate food, whether or not you wanted any. Answering "yes" often gets a follow-up about what exactly you ate, and whether it counted.
There is history under this too. Multiple generations of Vietnamese families lived through periods of real food scarcity — colonial-era famine, wartime shortages, refugee camps, the hard years after 1975. For someone who has been genuinely hungry, confirming that the people they love have eaten is not small talk.
It also travels. Many Vietnamese Americans notice their parents ask this on every phone call, sometimes as the first sentence, sometimes as the last. Some find it comforting. Some find it maddening. Often both, on the same call.
Not identically. The phrasing varies by region and household — some families say “ăn cơm chưa,” some say “ăn gì chưa,” some just start putting food in front of you. But food-as-care is one of the most widely shared patterns in Vietnamese family life.