Did they teach you that in order to have a better education you need to spend still more money per student? If money was the answer Americans would be the best educated people in the world.
But what you're not getting is WHY we spend more than anyone else. Yes, teacher pay is the largest single cost...but we've got a host of expenses in our schools that most other countries don't. For instance, buses. Yes, other nations have buses...but how many of them actually spend for big honking buses for the entirety of their rural areas? A lot of other nations use much smaller and more fuel-efficient oversized vans.
Another big expense is special ed. I've had medically-fragile Foster children in my home for nearly 15 years...and every public school in America (but not the private schools) is required to be able to transport, teach, and care for those special-needs children. Sometimes - as was the case for my kids - the school had to pay for a nurse just for my child for several years. Now the school's "only" paying for just a caregiver for him at school, as long as there's a nurse handy for emergencies like the short seizure he had today.
Another big expense is the cafeteria. Yes, a lot of other nations have cafeterias in their schools...but not all of them. Some nations require kids to bring lunches.
One of the biggest expenses is our school sports - NO other nation has to spend anything like what we do on sports, because just about every high school has both a football stadium (and football equipment and weight room) and a basketball court, and sometimes even a baseball stadium, too. These cost a LOT of money. What do other nations have? Sometimes basketball...but usually only soccer, if that...and even if they do have a soccer field, they don't have to spend anywhere near what we do on football equipment.
And let's not forget the newest big expense that our 2A-loving nation has in our schools that other nations largely don't worry about at all - armed security, sometimes even with metal detectors. We pay for that, too.
In other words, it's a big mistake to think that it's because of our teacher salaries that we're spending so much on education. We pay our teachers above the average, but our teachers get nowhere near the top pay (Luxembourg, $72K for first-year teachers (ours is $53K). It's all the other crap we're paying for that's making our education budgets so huge.