I think Finland and S. Korea are quite different from the US. These two countries have very homogeneous populations. In the US, we have many underclass populations like Hispanics, Blacks,and American Indians. Take out the scores of these underclass students and we are quite competitive (although still not as good as Finland and S. Korea).
Social/economic mobility is amazing hard to achieved even in the US. For Blacks, you have a group of former slaves and who for years suffer from discrimination. Native Americans suffered the similar fates. For Hispanics, you have the poorest of the Mexicans and El Salvadorians coming over the fences.
I have a coworker from Vietnam who keeps saying that his family came here with nothing but now he is an Engineer and his two of his siblings are a doctor and a Pharmacist. He argues that Black people in the US at least have the language skills and if they can’t make it they must be lazy. What he simply ignored is that his father was a general in the South Vietnamese government and his mom graduated from college in Vietnam. So my point is that if you are from the upper class of a country, you bring that education/knowledge/confidence/intangible upper class life skills to the US.
It doesn’t matter how much we want to spend, it is not going to help the people in South Central LA and Compton.