I was puzzled when Clive Crook wrote: “Public spending is lower in the US, but not vastly lower
once you remember to add state and local spending to federal outlays;
the US healthcare anomaly accounts for a lot of the remaining
difference.”  My impression was that, contrary to popular belief, U.S. government health spending as a percent of GDP roughly equaled Europe’s.

My impression checks out.  According to 2007 OECD data, U.S. government spending as a percentage of GDP is actually slightly
above the average of (Austria, Denmark, Finland, France, Germany,
Iceland, Ireland, Italy, Norway, Spain, Sweden, Switzerland, and the
UK).  As a percentage of GDP, the U.S. government outspends Canada, too! 
And since U.S. GDP per capita is higher, the U.S. government actually spends a lot more dollars per person than the average country in Europe.  Lack of U.S. government spending on health care is not the reason why our government’s share of the economy is smaller than Europe’s.