There is not single answer to your question. In general, they are okay if averaged out. US schools get a bad rap compared to other rich countries mostly due to

There is not single answer to your question. In general, they are okay if averaged out. US schools get a bad rap compared to other rich countries mostly due to some very tragic situations that make it impossible for some schools to do their jobs. For instance, there is a not insignificant portion of the student population in some places that do not speak English as a first language and sometimes at all. This is not necessarily the worst problem with our schools, I chose it simply as an illustration of something that can lead to low performing schools even if the school and staff are otherwise doing their jobs exceptionally well. On the other hand, the US also has some of the best public schools in the world. In a lot of cases, public schools beat out very expensive private schools in metrics like average AP score, average number of AP tests taken, average SAT, percentage of students at or above grade level, etc. At this high end, the US school system outperforms peer countries significantly. Its often the case that these high performing schools are relatively accessible for non wealthy people as well. You just need to rent an apartment nearby. You don't need to buy a property in Martha's vineyard. If these types of schools didn't exist, and the US public school system was as bad overall as it appears in the media, I suspect we would not have as many ambitious and highly educated immigrants wanting to live here.