I worked at the Fedex Hub in Memphis for 4 years and if there's anything I learned, it's that it's incredible that anything makes it through the sort intact. Training is pretty minimal and most of the learning is done on-the-job, except for around the aircraft. I think that a lot of companies that ship Fedex rely on volume rather than good packaging in order to move their product.
Damaging a package is not likely to get an employee fired, although it might earn them a reprimand.