Expecting gold out of nickels

A phrase often said by a person who has been hired for a low wage and does an adequate job but gets yelled at or talked down to anyways like they are hired you to be the second coming of Christ.

Manager: I told you yesterday to re-organize isle 22! You wasted a whole day!

Worker: I was told to put out stock and help unload the truck, you keep expecting gold out of nickels.