The problem, always and without doubt, stems from the teacher and not the student. Assuming the student doesn't have learning difficulties and does their homework and study.
Math is purely abstract. If the teacher cannot relate these concepts in a way that students can "grasp" them (analogies + examples), then the teacher is not doing their job. In many cases, I have found that the teacher doesn't understand the math concepts well enough in order to teach them to others. They simply regurgitate whatever is in their notes, which were given to them by the board of ED.
Worse still....is that most teachers are there to earn a living, and not necessarily to TEACH!