Americans don’t mind mandates in the form of payroll taxes for Social Security or Medicare. In fact, both programs are so popular even conservative Republicans were heard to shout “don’t take away my Medicare!” at rallies opposed to the new health care law.

There’s no question payroll taxes are constitutional, because there’s no doubt that the federal government can tax people in order to finance particular public benefits. But requiring citizens to buy something from a private company is different because private companies aren’t directly accountable to the public. They’re accountable to their owners and their purpose is to maximize profits. What if they monopolize the market and charge humongous premiums? (Some already seem to be doing this.)…

Moreover, compared to private insurance, Medicare is a great deal. Its administrative costs are only around 3 percent, while the administrative costs of private insurers eat up 30 to 40 percent of premiums. Medicare’s costs are even below the 5 percent to 10 percent administrative costs borne by large companies that self-insure, and under the 11 percent costs of private plans under Medicare Advantage, the current private-insurance option under Medicare.

So why not Medicare for all?