We used to talk a bit about the 80:20 rule in health care -- namely, that costs aren't even distributed, and that most of the spending comes from a small number of sick individuals (in other words, 20 percent of the people account for 80 percent of the costs). Lately, Peter Orszag, the director of the nonpartisan Congressional Budget Office, has been wandering around town with a graph showing the same thing in Medicare:
The implication of this is that to bring down costs you either need to make everyone healthy so they stop spending, or get better deals so their spending costs less, or get better information so their spending is more effective and they don't waste money. But when you're dealing with actual sick people, policies that make them spend a couple more dollars on the margin -- like the McCain plan -- are neither here nor there. They blow through the out-of-pocket caps in one trip to the hospital.
The implication of this is that to bring down costs you either need to make everyone healthy so they stop spending, or get better deals so their spending costs less, or get better information so their spending is more effective and they don't waste money. But when you're dealing with actual sick people, policies that make them spend a couple more dollars on the margin -- like the McCain plan -- are neither here nor there. They blow through the out-of-pocket caps in one trip to the hospital. 
