By Megan McArdle: While I was away last week, Vermont decided to scuttle its single-payer health-care plans. I predicted as much six months ago, for one simple reason: A single-payer system would cost too much. When faced with the choice of imposing double-digit payroll taxes or dropping his cherished single-payer plan, the governor of Vermont blinked.

“But Megan!” I hear you cry. “Single-payer systems are cheaper, not more expensive! Look at Europe!”