One of the most controversial areas in discussions of single-payer approaches for the United States, such as "Medicare for All," concerns its implications for costs. Confusion over differences between federal and total spending and effects of lower patient cost sharing gets in the way of "apples-to-apples" comparisons. Key areas with potential to lower costs are lower administrative costs and lower provider prices. But cost reduction would likely be smaller than some envision, especially in the price area because of the need for a long process to gradually allow providers to adjust to lower prices and Americans' unique attitudes toward regulation.