Citation needed. Over the last couple decades processed foodstuffs have been constant in price, but the portions have decreased to cut costs. You can play Russian dolls with old cereal boxes, fitting the newer ones inside the old ones.
Healthcare is expensive. Education is expensive. Land (in some places) is expensive. But man stuff. Stuff is cheap.
http://www.ers.usda.gov/data-products/chart-gallery/detail.a...
Similarly, if Apple could reduce its shipping costs to near zero by teleporting the raw materials to Foxconn and then teleporting the finished goods directly to retail outlets, they'd still charge $600 per iPhone, even though they have competition from other phone makers in the form of Android.
The Invisible Hand doesn't always work the way it did in Adam Smith's time.