I believe you may have misread these sentences because they're terribly phrased. The author isn't claiming that the US scores lower than Finland, South Korea and Canada because they're less lazy. Rather, he's claiming that although these countries score better than the U.S. in math, their algebraic skills don't make a difference past graduation. Rather, their perseverance helps them in their career pursuits. By extension, the author implies that US students can simply make up for a lack of algebraic knowledge with perseverance. Okay.It’s true that students in Finland, South Korea and Canada score better on mathematics tests. But it’s their perseverance, not their classroom algebra, that fits them for demanding jobs.
I can see why you thought I was confused; I agree the writing there is indeed awful. However, I was not confused at all. I had the same reading as you do on that paragraph. I still stand by my statement that his statement reads as "Americans are lazy, amiright," since he declined to provide evidence that other nations have greater perseverance or that their algebra skills make no difference.