Support for single-payer health care has reached an all-time high, according to Gallup. Seven in 10 Democratic voters — and one in three Republicans — favor a government takeover of the health sector.They should be careful what they wish for. Single-payer systems have failed everywhere they’ve been implemented, from the United Kingdom to Canada. Americans who fall for single-payer’s promise of “universal health coverage” at lower cost will instead find themselves facing long waits for subpar care.Support for single-payer is rising in part because voters don’t understand how such a system would work. Forty-seven percent of Americans believe they’d be able to keep their current health plans if the United States adopted single-payer. They wouldn’t. Just look at the single-payer proposals advocated by leading congressional Democrats.