- Supply and demand. People want burgers more, so they cost less (relatively).
- Storing fresh vegetables vs. storing meat and bread. Meat and bread have a longer shelf/freezer life and can be purchased in larger, and therefore less expensive quantities than fresh vegetables.
I don't think the comparison of a $1 hamburger and a $7 salad is valid. Take fast food restaurants in particular. A look at the value, or dollar, menu reveals not only a $1 hamburger, but also a $1 side salad. WHAT?! A comparably priced salad? Yes! And not only that, but the pricier salads often include a piece of chicken or other meat.
When I've dined at a fancier establishment, I've often found that burgers cost more than a salad, *unless* the salad comes with meat.
My assessment brings me to the conclusion that the original quote is faulty, in that it is comparing two vastly different things.
I'd love to hear your thoughts.