Most people haven't learned how to use a shopping list? What people are you talking about exactly (emphasis, as I'd like to know who you're describing here)?
I grew up in poor Appalachia. Every single person I knew, understood perfectly well how to use a shopping list, and how to cook. I simply can't imagine who these people are that don't know such things, given my comparison group is in theory low on the education chart.
Anecdotal: I grew up knowing how to cook and prepare meals since I was 10-11 years old or so. It was a complete shock after college to find out that my roommate (that I had gone to school with) could barely boil water.
I just assumed everyone knew how to cook at least basic things because that was how I was raised. He was raised with his mom doing everything for him, so after graduating (meal plans in college meant no need to cook), he literally could barely make toast. For the first 6 months after living together, his dinner usually came from Burger King.
Now I find that people my age (late 40's) and older are often the same way. Somehow they've managed to spend their entire lives eating takeout or microwaved meals.
In my single days, I managed to impress any number of women simply because I made them home-cooked meals. Insane, but true.
I rented a room from a woman who had her mother cook or she ate out. I had to show her how to turn on her own oven. She owned the house, had a beautiful kitchen (open, good appliances, lots of cupboard/prep space) but never used it. Her brother, also living in the house, was AMAZED when I would cook and make my own meals.
Combine that with misleading labels and massive advertising budgets of ready meals and it's easy to understand how people fall into the trap.