I think a lot of it comes down to economics, combined with how people have been raised. It costs money to learn how to do things. I've had to learn how to garden on my own (grew up near Seattle & a child of the welfare system - which meant I was limited on access to extra-curricular educational activities). I can tell you - it is expensive to learn how to garden well enough to be able to provide enough food for ones own family. I've been trying, and I can supplement my family with home grown food, but we certainly can't live off of what I've managed to grow.
Today, my immediate family is not poor, by poverty standards (in no way would our kids qualify for reduced or free lunches at school), yet our city has a lot of people who are. You can look up the demographics of any Washington school on-line at:
http://reportcard.ospi.k12.wa.us/ In our school, for example, 67.5% of the kids who attend get free lunches every single day - which translates to mean there are a lot of kids who live off of food stamps and food banks attending our school.
Our city is set up to teach people how to garden. The school system owns a garden and hosts classes to teach gardening skills to kids. The problem is, they charge quite a bit of money for kids to attend (for some reason, the # sticking in my head was $75.00 per kid). The kids who attend come from more affluent families. For families of low income, they can't afford to send their kid(s) to a class that is that expensive. Interestingly enough, our city provides free lunches to
all kids ages 1-18 who wish to pick up lunch in all of our city parks (yes, even my kids pick up free lunch if we're at the park at the time they are serving it). Many of the vegetables that are served come from the school garden. I've often wondered why the school system, if they're capable of feeding thousands of kids lunch for free, why don't they have a program in place to teach impoverished kids how to grow food.
As for county fairs, state fairs and Mother Earth fair... we're a family of five - it is very expensive to take a family of five to any one of those fairs. I wanted to go to Mother Earth this year - but we couldn't justify it in our budget. I certainly wouldn't expect a family who lives off of food stamps to be able to come up with enough cash to attend a fair in hopes to learn how to garden.
Could they learn how to garden on their own by researching in a free public library - sure, they could try, but there's a lot of time, skill and expense that goes into growing a garden. Many work 2 low-paying jobs just to pay the rent. Some may not have the money to pay the extra water bill, or to buy the rain barrels needed to provide "free" water. And, if they're not confident that what they plant will actually yield food, they could be hesitant to put the money into it.
It's easy to judge others who don't have similar circumstances as our own. But there are many facets to the problem of people learning to garden beyond telling them to go buy seeds.
Edited to fix the link.