Below is a link to a short but interesting Q&A from The New York Times.
In short (my summary),
Q. Why does organic milk have a longer shelf life than regular milk?
A. Demand for organic milk is less, therefore it has to travel farther to market. Therefore ultra high temperature (UHT) pasteurization (as opposed to HTST) is used for organic milk, which extends the shelf life.
All factually correct. However, by itself the illustration accompanying the article is misleading because there is no inherent connection between organic milk and extended shelf life. Marketing realities demand different processing techniques.
And this answer does not even hit upon the irony of many people buying organic because they think it tastes better. The negative effect of UHT pasteurization on taste is very apparent to anyone who takes the time to compare the two. So buying organic might actually provide inferior taste, due to market necessities.
As with any issue, when you dig down, nothing is ever as simple and straight forward as you might like it to be.