There are two things at play here in my opinion. First is that math builds upon itself. You can't do algebra without understanding operators, you can't do calc

There are two things at play here in my opinion. First is that math builds upon itself. You can't do algebra without understanding operators, you can't do calculus without understanding algebra etc... Second is that many feel math is boring, and they just zone out during the critical years. To get good at math, you need to assimilate concepts by playing around with them and doing the homework. Combine both these and you really have no way to tell if a person is lost because they are not good at math or because they've done #1 and #2 their whole lives.