I'm not sure the evidence supports that people are as ignorant as you're articulating. I certainly agree that public education is important, but we know the evidence tells us that public education alone is insufficient.
I'll just give you one anecdote. I'm just back from the International Congress on Obesity in Sydney and a very interesting study was presented in which they looked at school-aged children. They asked them in this case about advertising and whether they thought advertising was actually information, and they tried to understand whether kids thought advertising was real. Of the kids, 100% understood that this advertising was propaganda and that it was not real information, but 75% of those kids still asked their parents to buy the items that were being pushed on them as junk food.
While attitudes and awareness are important, the environment that those individuals live in is also critical.