I recently had the pleasure of hearing Barak Richman talk about the costs of medical billing, you know the extraordinarily byzantine world of insurance reimbursement, for providers. When you consider how much it costs a health care provider to get a bill paid, you gain some insight into why provider reimbursement rates are so high. Bottom line: at the academic medical center studied, it costs $20 to get a primary care visit billed and paid, considerably more for a specialty visit. Interestingly, this was not as easily attributable to the complexity of dealing with multiple payers with non-standardized contracts as you might guess.
More later on the causes of the expensive billing costs but it is worth noting that other health care systems based on private insurance have much lower administrative costs though they also have far more standardized or streamlined contracts and/or fee schedules.