One thing to keep in mind is that although there are a lot of elementary and high schools that do a bad job teaching math in the US, there's also a lot that do a good job. Kids that struggle in math in high school and/or come from high schools with poor programs mostly don't even try doing it in college. One other observation I've made is that people who do poorly in what I would think of as engineering math (calc 1-3, linear algebra, differential equations, probability and statistics, CS theory classes) often have more trouble doing the algebra error free than doing the "complicated" parts of problems. It's possible spending more time on algebra is actually beneficial to doing well in college level math.