I'm not sure what your point is. Is it about the lunches being specifically healthy?
A rice bowl at Chipotle, for example, is not unhealthy (rice, beans, meat, vegetables). Plenty of restaurant food in the US is perfectly healthy (or, you can look at nutrition facts to know if it is). And if I can take a single US portion size and split it into two lunches that are Japanese-sized portions, then maybe we're getting the same amount food per dollar.
And on the "healthy" point: The article doesn't discuss nutrition facts at all or refer to any specific meals or dishes.
They link to an article concerning the price of Japanese bowls, that mentions "a regular-sized bowl of rice with beef from Japanese fast food chain Yoshinoya, which costs around 468 yen (S$4.25)." I don't know Japanese so it's hard for me to find nutrition information about that particular dish, but I suspect that a beef bowl is high in saturated fat, cholesterol, and sodium (because most stir-fried beef is higher in these things). Is that healthy? Japan as a country has higher sodium intake than the US. Is that healthy? And so on. I suspect a big factor of the "health" of these lunches is that portion sizes are just smaller than in the US (but I have no data).
I think just statistics about how many people are overweight and obese in both countries can already paint a picture that probably japanese food is more healthy. And optimizing for how many calories you can get for $1 is probably also not the best metric to aim for.
Sort of for sake of argument: National obesity statistics don’t necessarily imply anything about the healthiness of the food, nor specifically about the healthiness of $4 lunches that the article discusses. If the Japanese eat smaller portions and are less sedentary, they could still be less obese regardless of differences in the nutritional content of these $4 lunches. (And I think they ARE less sedentary and DO eat smaller portions.)
I’m not advocating for anything (certainly not optimizing for calories per dollar).
My point is just that the article has no data. It says a Japanese lunch is cheap and a US lunch is expensive and doesn’t consider what you actually get for the money. It assumes the US lunch is a worse deal, but I suspect it’s really not if you adjust the price for the amount of food.
The title doesn't capture that, but the issue is not that the US can't produce $4 lunches. It's it can't enable cheap(er) healthy lunches