I ate everything that I saw in Vietnam. Street food, restaurant food, food down dark allies. For months. Only had ONE single issue. For an hour. That's it.
Maybe you have a really strong stomach? I've spent weeks in Thailand, often in pretty rural areas, and never got sick there either. But it's not like I'm the only one having problems with Hanoi's food:
https://www.sciencedirect.com/science/article/abs/pii/S09567...
https://www.who.int/features/2015/food-safety-interview/en/