We used to make baby food ourselves. That was like twenty portions of baby food in ten minutes, for pretty much no cost (all basis fresh staples are pretty much free: fresh carrots, potatoes, rice, onions, pumpkin). Chop some vegetables and perhaps add little leftover meat, steam it, blend it, freeze it. Philips had a great machine for that. But we were somewhat 'out there' here too. Most people give babies food from glass pots. Then I see [1]. Got healthy teens now who eat pretty much everything. We still cook most of the stuff ourselves, although time constraints are a bit harder now than a decade ago.
Same as for walking. That is the most basic instrument for health. But if you cannot go out for a good walk because your environment is car only, what can you do? You can sanction the car makers for not making us walk. But that's a bit silly? (You are not saying that, trying to make an analogy with the food producers.) I'm blessed with lots of forests nearby, with separate paths for walking, cycling, MTB-ing and horseriding. Going outdoors is trivial here.
Point I'm trying to make is that an unhealthy and sedentary lifestyle is a lot of factors working combined. That's why international comparisons are so hard (or impossible). I think the 'Boulder, Colorado'-lifestyle is comparable with my local EU-lifestyle. But all environments are different on many vectors.
[1] Nearly two-thirds of baby foods in US supermarkets are unhealthy, study finds - https://www.youtube.com/watch?v=DXyVJpTe8NQ