The supermarkets in my area have abundant fresh produce. People don't want that stuff. They want sugar, fat, and salt. Pizza, KFC, hamburgers, potato fries, bacon, BBQ meat. Anyway you get the picture. The stuff that tastes good.
I browse a forum with the heading"What's for Dinner". This is what they ingest.
http://s7.zetaboards.com/Worldwide_Seniors/forum/3034163/ I am almost sure this is typical of all Western countries.
Also produce usually has a short life span and preservation takes effort and time. If people have the economic means they will follow the path of least resistance and purchase prepared food.
Also people are often Pavlov's dogs and associate food with all the comforts of life. In fact this is often their only life. Hence the significant obesity throughout the world. Good or bad, who knows? Also we have given our food processing over to commercial interests, probably to the detriment our our overall health.
I live in the best growing area in Canada. The urban properties often have large properties and nary a vegetable garden in sight. Our growing season is short probably at most four months. Preserving methods to produce palatable food is as difficult today as it was years ago with a few exceptions.
This garden forum does not even have preservation section?