While the parent may be off a bit, the quoted article times are ridiculous unless you are counting "man hours" including transport to/from the railcar and stacking on a shelf. It is absurb to think that a single boxcar would be staged on a busy warehouse spur for 3 days of loading or that a modern palletised boxcar takes 3-4 hours to unload with a forklift/pallet jack (it takes about 30min or so).
Long ago I worked a Target dock unloading trucks by hand. Depending on the store volume and the season, that would mean unloading between 3000 and 10,000 cases from 53' trailers each night, 5 to 6 nights a week. Unlike Walmart and some other stores, Target merchandise all came stacked in the truck except for a few bulk items (kitty litter/etc.), it is individually bulk-broke from the warehouse to restock each item depending on the previous days sales. (A large case count on an incoming truck always made us groan as it probably meant lots of deodorant/hair products which come in small 6 count cases.)
A typical 6000 case trailer, including setup and teardown time, would take approximately 2 hours to unload. 2 people in the trailer placing boxes on a conveyor, 4 to 6 people pulling/sorting boxes off the conveyor and on to pallets for storarge or delivery to the floor. If you extrapolate that to a 13,000 piece count you get roughly 24 man-hours, or "3 days" assuming a single 8-hour shift.
Likewise, I also worked a different warehouse job forklift loading 53' trailers. If all of your stock is pre-staged on the dock it takes about 15min to load a trailer. If you are pulling every pallet from the racks and transporting it to the trailer individually it will take 1 to 1-1/2 hours plus. Again, extrapolating that to an 85' boxcar you get roughly 3-4 hours.
So.... the only way you get the articles quoted loading/unloading times is you are counting man-hours including transport/, not literal time as is implied.