Cross-subsidies are the original sin. The government wants to subsidize health care for poor people, chronically sick people, and people who have money but choose to spend less of it on health care than officials find sufficient. These are worthy goals, easily achieved in a completely free-market system by raising taxes and then subsidizing health care or insurance, at market prices, for people the government wishes to help.
But lawmakers do not want to be seen taxing and spending, so they hide transfers in cross-subsidies. They require emergency rooms to treat everyone who comes along, and then hospitals must overcharge everybody else. Medicare and Medicaid do not pay the full amount their services cost. Hospitals then overcharge private insurance and the few remaining cash customers.
Overcharging paying customers and providing free care in an emergency room is economically equivalent to a tax on emergency-room services that funds subsidies for others. But the effective tax and expenditure of a forced cross-subsidy do not show up on the federal budget.
Over the long term, cross-subsidies are far more inefficient than forthright taxing and spending. If the hospital is going to overcharge private insurance and paying customers to cross-subsidize the poor, the uninsured, Medicare, Medicaid and, increasingly, victims of limited exchange policies, then the hospital must be protected from competition. If competitors can come in and offer services to the paying customers, the scheme unravels.