I would not underestimate the importance of US dietary guidelines.
For example, dietary guidelines are followed by schools, hospitals and military. They are also taught in medical schools and used by doctors to advise their patients. Additionally, lots of countries semi-blindly follow whatever guidelines US comes up with (see the parallel with covid treatments & measures?)
My gut feeling is that those guidelines directly contributed to a vast number of deaths / lost QALYs.
The effect could be different in Vietnam because of cultural differences, strictness of regulation or somethings else. Same as vaccine program compliance.
The central point is about adequacy of governmental decisions, not about compliance to them.
There are plenty of regulations about hospital food or child nutrition in the US that follow the dietary guidance. I have not looked into it but it would not surprise me if they regulate macro calorie intake for military (not that it matters for the central point of discussion).