A McDonalds salad costs more than a Big Mac because McDonalds salads typically come with meat (chicken or bacon). Both of those meats are at least as expensive as ground beef. The rest of the stuff in a salad (veggies, cheese, dressing) are more expensive than the rest of the parts of a burger (bun, condiments). A salad is also more labor-intensive to put together, and requires greater care to avoid contamination.
When I make burgers and salads at home, it costs me about half as much for a dinner plate sized salad (no meat) as it does for a quarter pound burger.
One point I didn't see mentioned in the article is that in the case of the Big Mac, it's likely that McDonalds sells the burger at a lower profit margin so that they can sell more fries and drinks (the real moneymaker). I'd like to see the data, but I'd bet that 95% of Big Macs were sold as part of a combo that included fries and a drink, and 95% of salads were not. To my knowledge, salads are not included in any value meals at McDonalds. Couple this with the fact (mentioned in the article) that the ingredients in a Big Mac last longer in storage than those in salads.
When I make burgers and salads at home, it costs me about half as much for a dinner plate sized salad (no meat) as it does for a quarter pound burger.
Food subsidies are not the major cost driver.
Previous comments on this subject: http://news.ycombinator.com/item?id=1299264 (me) http://news.ycombinator.com/item?id=1179551 (cperciva)