That's because: (1) it's rich in toxins due to the industrial processing and (2) it has a poor proteins/nutrients to energy ratio.
Nutrient hunger is a thing. Proteins are regulated by the brain. Micro nutrients might be regulated by the brain as well. When you eat ultra-processed food, you end up eating more food just to get the nutrients you need to live.
Ultra-processed food is also rich in calories, often being high in carbs and high in fat at the same time, a very unnatural combination that floods the brain with dopamine, making you overeat and crave for more.
You basically can't get lower quality than this.
> "as opposed to unconstrained individual choice"
There's no such thing, you're not aware of many of the recent findings.
I recommend you go read: https://www.stephanguyenet.com/thehungrybrain/
(2) is a valid point, but (1) should be entirely prevented by the FDA.
But again à lot of it is a question of dosage. A bottle of coke a week might not do much, a bottle a day and it's a whole other story.
"The most neglected threat to public health in China is toxic soil" -- https://www.economist.com/briefing/2017/06/08/the-most-negle... (2017)
All the things in their air and water (Quote from the article: "Wen Jiabao, a former prime minister, once said that water problems threaten “the very survival of the Chinese nation”.".