Organic foods produced by sustainable farming methods rely on natural processes that are non-chemical, and that are not exposed to any chemicals for a distance of three miles around the production area.
Just getting certified as Organic by any organization other than the USDA is costly and extensive. USDA certification, while I do not have firsthand experience, due to pressure from major producers and manufacturers feeling the impact of Organic products in the stores, more than likely negotiated a much less strict adherence to organic standards. I wager that if USDA were compared to say, Oregon Tilth, there would be a significant difference.
So, as to why more expensive? The methods are more costly, more laborious, no chemical fertilizers, pesticides, and all these processes have a cost factor. The results are far worth it, and it pays off in the mouth! Not only that, it pays off by giving your body what it needs, and not all the things we have had feed to us by industry that have been killing us for decades.
Compared to 30 years ago, Organic produce is more plentiful, and the cost has come down tremendously. The Organic Industry has enjoyed an average 10% annual growth for the last 15 years. That's why BIG BIZ wanted a piece of the pie.
Hope that helps a little.
