The numbers are eye-popping: $25,000 MRIs, the $1,000-a-day hepatitis B drug, $629 for an ER visit that only delivered a Band-Aid. As leading health care economists bluntly put it in a famous research paper, “It’s the prices stupid.” Experts increasingly point to the high cost of care in America — not necessarily the overuse of care — as the chronic illness of the U.S. system. Health systems in other developed countries pay nowhere near these prices for the same services. And while the Affordable Care Act changed who pays for health care, it has done little to curb rising costs.