I am puzzled by your question. Yes, some students struggle at math while others do well in it. But the same is true of History, English, French, and just about every subject. Different people have different talents.
As a tutor one of the biggest hurdles is sometimes convincing the student that they are in fact capable of understanding the subject.
We can add to this discussion the academic background of math students. Some students went to better schools, received better training and thus can do the math.
Others lack the solid educational structure needed to exceed in math after middle school.
I am no math wizard but the basic skills I do have has been the result of years of self-study. I took precalculus in 1993 as an elective course and got an A minus.
in my opinion you learn best if there is an urgent need to learn. For instance: If you are very hungry you learn very fast how to steal or to hunt.
In everyday life there isn't a need to do math beside some adding or proportions. Even though you're an engineer or a banker the computer will do it and nobody is forced to learn about the math which is implemented in such a machine.
A good math tutor doesn't make his pupils to swot up (is this the right expression?) rules, numbers, laws etc. but awakes the insight of his pupils that math is a necessary and substantial part of their lives. And then everything else will be done by the pupils themselves- with a little help from their tutors, of course!