Firstly, students get more information than they did in the past. Years ago, when internet didn't existed and TV and radio were the privilege of few rich family, children or students had only limited channel to get information. Therefore, teachers exert dominant influence on students since teachers were the most knowledgeable person around students. Students seem to believe whatever said from their teachers even if what said by teachers were wrong because students can not verify the information. Nowadays, students can get tons of information from TV, radio, especially the Internet, which can help you to solve most of your problems. Some students are becoming more knowledgeable than their teachers in some field.
Least but not the last, teachers are becoming less interested in their job. When I was a student, I remember teachers were pretty enthusiastic about their job, they will devoted all their energy and time to nurture students both in academic and in psychological health. I remember when I was a junior high school student, I have some hard time in dealing with studies due to my secret crush on one of girls in my class. I didn't know my class advisor noticed that, and he have a very long conversation or communication with me. I appreciate what he has done for me since I would not go into college without his instruction. But nowadays, teachers are less care about their job. They choose to be teachers is not because they loved to be teachers,but because being teachers is a comfortable job and pay well. Some teachers would like to be private tutor for other kids just to earn some extra money instead of taking care of their students in the class. Therefore, students are becoming less trusted about their teacher.