We know young kids learn through play yet we continually force them to learn through the equivalent of lectures.
For older students that can learn through lectures, we insist on giving in-person lectures. This means that 99.9% of students are taught by sub-par lecturers. Highschool and college students are foolish to attend lectures person. Instead they should just watch the best in the world on opencourseware/youtube.
Hands-on lab experience and group work is useful and difficult in a remote setting but a very small amount of HS/college time is spent on that. I'd argue pretty much all in-person HS/college time should be spent on that.
We still attempt to teach the mechanics / tools first, like math and calc before the motivation. We do this even though we know that the human brain generally ignores information without utility. We should instead provide students a long-term goal they are interested in and introduce math / calc / physics as a means to achieve that goal.
Most first world countries are well above the US’s 5% GDP in public education expenditures; schools absolutely are underfunded in the US.
It may also be unusually poorly administered, but this isn't like healthcare where US public spending is on par, as a share of GDP, with other developed countries despite doing far less with it.