Your understanding of how formality levels in English function is perhaps not entirely complete: native speakers of English convey usually convey the sentiment with as little as "Breakfast?" or "Hungry?" when talking with family. In the child's second language, would the maitre'd at the restaurant of a fine hotel ask a two word question, or rather bury those in respectful filler?

"Ow" and friends, by the way, are interjections to express sudden pain, functioning analogously to an adult's swearing. They're not full sentences about the pain and its source.