Staffing

Why is it so hard for people to staff work areas? Why can't you just put someone in the job they want to be in......I don't get it. Why make someone do something on a daily basis that they do not want to do? Who's fault is it when they do a crappy job: the worker bee because they don't conform when they have no desire to do it or the supervisor that can't manage/has no choice? I think it then becomes the supervisors fault. Why would you have someone sit at a desk that would rather paint when you need someone to do both? Let that person paint and have someone sit at a desk. We have plenty of people in the world that would love to sit behind a computer all day. I just don't get it!