First, students' own wishes, they don't want to go to school, and they feel that they have to start to enter the society after graduating from college. It is better to enter the society early and achieve independence.
Second, family reasons. Some students' family conditions do not allow them to support their college education. Although there are many poverty alleviation policies, they can only help some people.
Third, the college entrance examination. The college entrance examination will screen out some people and prevent them from going to college. Even if family conditions permit, students want to go to college themselves, but a good university is not so easy to take an exam, and it depends on students' grades. Otherwise, why is there a difference between focusing on one book and two books? Of course, universities are everywhere now, as long as you want.