The problem is, depending on who you talk to, there are thousands of things like this that a person "should" know. I wouldn't even know where to start or who to believe on even this one topic.
You could distill the original commenters suggestion to teaching children how to research and always find ways to learn a bit more about what they're told or what they're doing. That way it can be applied to food origins or newspaper articles or receiving financial advice.
There are a number of basic life skills that go untaught during school years - personal finance being one of them.