Ever hear of food deserts?
Not saying it's the main cause but it's similar enough to the primary issue.
A fair portion of people that are unhealthy/obese are low income, and buy processed foods since they're the cheapest, or most caloric dense, it's a struggle to eat healthy when they infrastructure surrounding you makes it more difficult.
Also many other variables like stress, and impulsiveness, etc.
That being said I do realize it's about choices too but that becomes a hurdle when better choices aren't given to you.
(And yeah I know request the brand in the store, or buy it online, etc. , I'm just offering a different perspective)