As a matter of fact, if the US school system is partly or significantly responsible for the productivity and creativity of adult residents, I'm pretty satisfied with it on the whole. I'm not sure studying to tests produces the best outcomes. I'm more interested in novel problem solving, invention, and innovation, and typical international standardized tests don't suss that out especially well, do they?
Moreover, it's hard to know what to infer when comparing a giant, multicultural country with a small, much more homogeneous one such as Singapore. It makes sense that some small countries might outperform the US at testing in the same way that you expect some small countries to have a higher per capita gdp. Unless I miss my guess, we could cherry pick some communities in the US that do better on either than Singapore.
This article about US test scores, after adjusting for demographics, was discussed on HN before, although I can't find the link just now:
http://super-economy.blogspot.com/2010/12/amazing-truth-abou...
It's extremely interesting, and I haven't seen anything that impeaches it.
That's not to say that I think the US school system does not have huge room for improvement. That's clear, and I'm hopeful that continued technological development and research will provide amazing breakthroughs. Moreover, we're not even using some of the best methods that are already available; research suggests the Montessorri method is advantageous, and indeed my own son was trained at one, and we were much happier with the result in comparison to his time at a public elementary school.
But it's not necessary to down talk where we're at to motivate improvement. What I don't want to see is throwing the baby out with the bathwater. US schools get some things right. Students come out believing they can do anything. They're not afraid to try new approaches. I'd rather not end up with test taking automatons who are mainly expert at memorization and thoughtless skills drills.