That's because you're biased. Its a small trend over a long period of time that doesn't outpace the cost of living. There is also a massive shortage of farmers thanks to big agriculture killing them all off.
Most farmers want to own the land they work. Good luck with that in CA
I read there's a 50% increase in wages, during a period when CPI is up more like 30% in California [0], and I'm saying I agree with the article: it seems like a reasonable economic incentive.
To respond to your comment: isn't a farm worker different from a farmer? I thought the former was someone who does things that require little to no training, like picking grapes, and that these are the people the article references.
0 - http://www.calrecycle.ca.gov/LGCentral/DivMeasure/AdjustMeth...