The cheap stuff gets an economy of scale if you do a lot of it though, you can probably binge pack 20 items in an hour, whereas single higher price items sold infrequently you probably take half an hour, finding the stuff, getting set up, packing it, putting stuff away. I think probably the cheaper stuff makes $5 total per item anyway between actual price and "handling" charge. Though not the "too good to throw away" one offs. If it's business oriented rather than private sellers, they probably do volume to keep themselves in a small commercial unit where UPS does pickups. Then also there's some sellers who are basically small scale defrauding their employers, every item is worth $20 to them, because they ship it on the employers account and pocket the shipping.
Even cheap stuff just sits and sits though. A decade back I had a couple of boxes full of stuff from a relative's estate, sorta collectables, think like Hummels and Wades but not the rare stuff. Priced between yard sale and fleamarket it just sat and sat, months, never sold one, though similar stuff was selling. Actually I remember one was a virtual face slap, listing at 3x the price of mine for same piece, visible chip off the base, dings in the detail, seller didn't have much more feedback than me, sold... while mine, not a peep. Maybe there's such a thing as listing too low. I've come to think it's probably better to list high and then take reasonable offers.
Unicorn herding operations are proceeding, but all the totes of hens teeth and barrels of rocking horse poop give them plenty of hiding spots.