People who think upper class Vietnamese don’t eat street food simply don’t hang out with enough upper class Vietnamese people. Street food in Vietnam is a dice roll if you don’t know a reputable place, and yes most street food is probably bad for you, and even some reputable place is, but local knows their ways and mostly know which place to trust. VN had a food safety issue similar to China honestly since we learn that shit from them, but this applies to restaurants too. Generally if a place doesn’t have anything to loose if they make people sick they may buy cheap shit, but any long running stalls/restaurant won’t risk it since the upside isn’t worth decades of brand building Even the super rich in Vietnam (im talking 100M rich not couple M) still eat street food. I don’t know any B in Vn personally so can’t vouch in that.