That's the big lie the right wants you to believe; there's no such thing as unskilled labor. You have to learn every job you start. Flipping burgers, packing boxes, cleaning, washing dishes, etc all have a learning curve. There is no job you can walk in off the street and start doing without previous knowledge.
As a former warehouse worker and shipping clerk, it is 100% unskilled labor. We would sometimes hire temp workers for really busy periods, and it would take about 30 minutes to train them.
Yeah, and as someone who works in QA for a carrier repacking some of those boxes I can tell. Shippers really don't seem to care that their packages don't even make it to the shipping phase, let alone through our damn building.