Is it common to ask students to help the teacher in the teacher's normal duties? It seems quite common for other teachers at my university (in Asia) to have students help with what are the normal duties of a teacher. Examples range from asking a student to help carry one of many stacks of books (because the teacher cannot carry all of them) to asking students to carry very small things (which the teacher could easily carry but the teacher would prefer not to carry anything at all and let the student do it) to having students complete marking sheets for graded assignments (where the teacher has already decided what the marks should be but prefers to have a student do the typing and printing).

It's very strange for me because I've never seen it in my own culture (which doesn't mean it doesn't happen), but I'm not Asian so perhaps I'm just not yet adjusted to the local culture.

Do most universities allow a teacher to put some of the teacher's regular duties on the shoulders of some students? 

Note: This has nothing to do with teaching assistants, I'm just talking about regular students who appear willing to help (either to learn/understand more, to get in good graces with the teacher, or perhaps for other reasons I cannot see at this time).

[EDIT] I've modified the questions slightly away from ethics towards being common due to concerns from other users feeling it was too much of a discussion / opinion question.
Confucius once said (in a rough translation) "It's student's job to serve the teacher when the teacher needs help." (the source in Chinese)

I think in most places, where Confucius's principle is still being followed, helping the teacher in his normal duties is considered normal.

However, help marking the sheets is not normal as far as I understand. At least, Confucius never graded his students. He did have comments about his students, though.