No, they should not, because if the student is very self conscious about how they look through the camera or just in general, it can give them bad anxiety and people can also be rude.
Yes, a teacher should make it mandatory for students to have their cameras on Zo om. (This is my opinion)
Explanation:
Many students may completely ignore the lesson when their camera is off and the teacher would no be aware of this. During tests, quizzes, or assignment students could easily cheat while their camera's were off and the teacher would not know. It is my belief that some students are irresponsible and can take advantage of a turned off camera.