Instead they argue that the lower European GDP/person represents mysterious cultural differences, a preference for leisure,
I've long thought the effect of taxation on work was overblown. If we taxed 40% of GDP for military and nothing else, people would work far more than if we taxed 40% of GDP and fully funded health care and pensions. Once health care and retirement are taken care of, people will work less. There is evidence for this in the CBO report for ACA (from factcheck.org):
In fact, CBO did not predict a 650,000 job loss. The Republican report cites a CBO report from August, which actually said that the economy will use less labor primarily because many people will choose to work less, or retire early, as a result of the new law. (See Box 2.1, pages 48 and 49.) What CBO projects is mostly a reduction in the supply of labor, which is not the same as a reduction in the supply of jobs.
In other words, it's not so much taxes discouraging work, as the benefits taxes pay for discouraging work. I don't consider myself atypical, and I can tell you for certain that I would retire earlier, or change to a more leisurely, lower paying profession if I didn't worry about paying for healthcare. Healthcare is the largest uncertainty in my future spending.
I'm not saying it's right to fully fund healthcare and pensions, in fact I would lean toward only partial funding in the interest of more growth, but to ignore the benefits provided by European countries compared to the U.S. and put all the blame on taxation is simply wrong.