That article is several years old now, and maybe there are some regional factors at play, but as a farmer myself, these days I regularly see offers of $20/hour if you're willing to show up, and closer to $30+/hour if you bring any skills to the table. Despite that, there is still is a lot of struggle to fill those jobs.
And maybe the price just needs to go higher still. I'm not going to tell someone how much they have to work for. But it's interesting that – once you account for the significantly lower cost of living generally found in these rural areas – you're practically making programmer in a big city wages now and that's still not appealing to someone who is unemployed.
In a lot of ways, I think enraged_camel (and cobo) hit the nail on the head[1]. Nobody wants the identity of working on a farm. There are a lot of negative connotations related to that type of work that have been built up over the years.