We have some very strong HS programs in the US, as well. On the flip side, there's a wide range in how much different school districts spend (and are able to spend) on students.
I don't know if it's too much that we think of them as babysitting centers. I think it's more that a lot of communities are allowed to resist the investment in education that other (more affluent?) areas are quite happy to spend. There's also not infinite resources, of course, so to an extent it's a distribution issue as well.
If you have a community that supports the school with families who instill education as important....then yes, spending more will improve education.
However, there are lots of school districts where one heck of a lot of money is pumped in but the community around it sucks so bad that the education still sucks and pumping millions more in isn't going to make a big difference.
No, that statement doesn't mean I'm against spending more on education. But, let's be honest about what those results are going to be. Until a student's family life instills the idea that education is important and so go work hard and get good grades to improve your life....well....that kid's chances of improving his education is pretty slim.
I think it's also pretty meaningless to look at what we spent per student 50 years ago and compare it to now. 50 years ago, we didn't have the technology that's needed in schools to really prepare the student for what is expected of them in the work place once they are out. That technology is expensive.
Now, personally, I think our school systems are doing a pretty dang good job with some obvious major exceptions that need improving. My kids go to public schools and they have received a very good education that has allowed them to go to college and succeed. Our school also is improving on the vocational education for people who are not going to go to a 4 year college.