I've been following this thread with interest as it is something that I'm working toward living out as best as I can. I think that the key to this is knowledge and the moral fortitude to swim against the tide. The system is a mess, from how we produce our food to how we treat our labor.
I'm not entirely sure that I buy the argument that these jobs are so horrible that Americans won't do them. Plenty of Americans did these jobs in the era between slavery and the influx of illegal immigration in recent decades. Often, these jobs were done by teens who were working to help support their families or by men who needed to work extra jobs in order to bring in enough to live. My husband and his cousins ALL picked berries in the summer months. Did they make a lot of money? No. But, they did it anyway because it was an opportunity to earn an income in the summer months. Every single one of these men now have advanced degrees - two with PhD's, one with a Masters, and one with a BA. They're doctors, scientists, teachers, and managers. It was NOT beneath them to do this.
I think the problem starts with how the powerful treat the powerless. As long as we justify that someone is beneath us for whatever reason, we can justify the way that we treat them. Do these jobs HAVE to be as perilous as they are or are their ways to honor the dignity of every human being, no matter their status in life, by providing them with a safe environment in which to work?
So, what to do? Why don't YOU start a community garden? It's not always as hard to do as it seems. We did just that last spring, on a 1/4 acre weed lot at the back of our church parking lot. It's planted in fruit trees, herbs, and vegetables. Those who work it are free to take what they NEED and there is no charge to participate. The rest is split - with a portion offered to anyone who wants to donate toward the support of the garden and a weekly supply is taken to a local homeless shelter so that we can share with those who are struggling. The donations support the cost of running the garden and everyone shares in the work.
Even in crowded So Cal where I live, I see plenty of plots that could be used for this purpose. I hope that someday these will sprout up with good things to eat, grown organically and using sustainable methods. We who care can be the flag bearers of this new trend. We just need to step out of the system, pester our representatives, and DO something ourselves. And, most of all, we need to stand up for those who are powerless to do so. They may not have rights, but WE do, and we should use them for the good of all humankind.