Why do people need math tutoring?

Anyone who knows arithmetic has demonstrated mathematical ability. They are capable of recognizing mathematical concepts, memorizing logical rules, and applying them in the correct context. These abilities should be sufficient to master everything from Algebra through Differential Equations. It's just a matter of time and effort. Admittedly, some areas of study, like Higher Math, may require additional skills. How could it be, though, that so many stud...