Right, and that's kind of my point. It's not just the way we eat in "modern society", but the way we have come to simply throw drugs at every perceived health problem instead of looking at better options.
We know what all of the better options are, people are not availing themselves of them. That makes better living through science necessary, if we are to help the people that will not or cannot help themselves.
The issues you brought up about pricing, availability, and access, is another subject. Poorly regulated capitalism, in which the companies effectively write the legislation here in the U.S., is the problem as I see it. Easy fix as solutions go, but the hardest to institute. As it requires doing what's right, instead of what's best for the companies and congress critters bank accounts.
As I understand it there are a lot of several factors playing a role.
Social/political
Is healthy food readily available and can be bought by every income group?
Are healthy food available as ready meals and in school or other public kitchens?
Are unhealthy products clearly labeled and are the strict regulations about what can be put into your food?
Stress often leads to overeating. Do we as a society have a stress problem?
Is obesity evenly distributed in the population are some social, cultural etc. more dominant?
And then there are personal, like genetics, family traditions, upbringing, personality etc.
It's all of those things and more. The take away for me is that if science can help, even if it has to be incentivized through profits, it should.
Actually not true. Talk to someone who's spent a lifetime fighting with weight, about 6 months after starting keto, and let them tell you how much a calorie is worth.
Good book someone here recommended way back -
https://www.amazon.com/Good-Calories-Bad-Controversial-Science/dp/1400033462
I know it's not without its issues and critics, but people that follow the principles get results. As you pointed out those same people yo-yo dieted at best before adopting the strategy. Anecdotal evidence carries more weight (I'm a punny guy) when there is so much of it.