I'm not advocating that putting more money in the education system alone is a solution, but considering that nations that spend more and those that spend less as a % of GDP get both better and worse results suggests it's not as simple as suggesting that more money won't help.
If a lot more money is going to spent, it ought to be spent to address the root issues in poor communities (unemployment, lack of security, healthcare), whose effects ultimately manifest themselves in the classroom. What's unlikely to help educational outcomes in poor communities in the US is continued divestment and chalking the problem up to "cultural" issues in those communities.
However, as I pointed out elsewhere, if we continue to expect (as we currently do) teachers in poor communities to function as social workers for the problems created by divestment instead of addressing the socioeconomic issues at their root, then we should pay teachers more for providing those services in addition to teaching.
Vietnam is an interesting example, thanks for sharing. Notably, according to [1] it has a centralized state-run public educational system where public schools are directly administered by the government. Vietnam is also an authoritarian, single-party, and nominally communist society. That level of socialist-style centralization is not feasible (or even desired) in most parts of the US, where even at the state level, the government stays relatively removed from the day-to-day administration of the schools.
Vietnam's education system is a complete shit show. Teachers earn scraps leading to a semi-open practice of education related bribery. Resources are all but nonexistent and invariably outdated. Native teachers tend to be poorly educated, whereas foreign teachers are a mix of sexpats and backpackers. And I'm not entirely sure what you are trying to imply with their government, but the nation is not communist. It has a single authoritarian party that oversees a market economy. The only semblances left of communism are an extremely poor people and the complete lack of any freedom of speech. Schools in many cases are practically falling down.
Regardless, the nation somehow is producing even more capable students than the US. When I was young I also went to a incredibly poor urban school. And I also had numerous Vietnamese individuals in my classes who I remain friends with to this day. In an interesting coincidence they too, in spite of enormous adversity of our youth, went on to all do well more than fine. Of course that's completely anecdotal. In looking for demographic data I was completely unsurprised to see Vietnamese well above the median in terms of US median household incomes. [1]
So what's their secret sauce? Whatever it is, it's unlikely to be replicated by just throwing money at the problem anymore than you would manage to turn lead to gold with good intentions and lots of dollars.
[1] - https://en.wikipedia.org/wiki/List_of_ethnic_groups_in_the_U...
My comment was meant to highlight the disparity between districts. You can pit the best US students against the best students from any country and get excellent rankings. Our worst students are far worse then other developed nations. We need to address the systematic problems in our country that are causing us to value certain students more, and give them better opportunities. All children deserve opportunity.
In school I felt I always worked hard, or was somehow more incentivized for the work than others. The harsh reality, apparent in hindsight, is that I was lazy and it came to me easily - as it does to many people. In teaching you one begins to quickly appreciate that inherent differences between children is absolutely night and day - and these differences emerge even as early as elementary.
These inherent differences are the giant elephant in the room that nobody wants to consider. In my opinion ignoring them and pretending that all we need to do is give more opportunity or money to some schools is doing us all great a disservice. A near majority of the kids in the classes I taught I could personally adopt and give them 24/7 attention and education at home and I suspect they would still fall well below the curve.
What is the solution? I have absolutely none. But at the same time I think that complete and open honesty and assessment is the first step to resolving any problem. When we start with false assumption as its more socially palatable, is it any wonder that we spend all of this money with absolutely nothing to show for it?