A. Jewish tradition considers it a (reluctant) honor and obligation to participate in a burial personally, instead of letting the hired help with the backhoe do it. As much as we would rather never have to do it, burial is a Mitzvah, and an important way for family and friends to honor the deceased.  The reason why its traditional to do the first shovelful or two with the shovel backwards/upside-down is to show our reluctance and sadness.