The U.S. spends much more per manual laborer, nanny, etc. The wage level is higher, and immigration restrictions prevent wages from equalizing across national borders. You have to ask whether the U.S. has more or better teachers, or textbooks/facilities/amenities, as opposed to paying more for similar or lesser inputs.

Also, spending reflects other factors to some degree, e.g. it is more labor-intensive, and thus expensive, to educate children with learning disabilities or other serious problems.