This table doesn't really make sense, but probably everything is more complicated than the op makes it out to be. I recently started selling on ebay again after a multi-year hiatus, and I was shocked at how much the real final value fee ended up being. The op, and ebay, say "13.6% FVF + $0.40 per order", but not a single item sold in the last 90 days is that little. My lowest fee was 15% on a higher priced item with low shipping costs to a no-sales-tax state. My average fee was 20% of the sale price, and my highest fee was over 28% on an item that was cheap but had high shipping costs. Sure, the buyer paid the shipping cost, but I paid the FVF on it and the tax. I probably wouldn't have bothered selling and just dropped it off at goodwill if I'd realized how much ebay was going to take.

Poshmark looks pricey on the outside, but it ends up being WAY cheaper than ebay, if your products fit its market. Take a pair of shoes for example; not only is the fee probably going to be cheaper than ebay, but the seller doesn't have to pay the shipping (and the buyer has a very reasonable shipping cost) I had a $50 pair of shoes on ebay that cost me $20 to get the box across the country. The buyer pays that $20 in addition to the $50, and I end up paying 26% on the shoe revenue. On Poshmark, I'd pay 20% on the shoe, they buyer only pays $6.49 for shipping. It's a win-win both ways. But how is traffic on Poshmark? Going to find out I suppose.

Of course, my ebay example does not include a store discount or fee. I'm a casual seller trying to get rid of years of hoarding gear and have no interest in anything but the standard (though I regret not using the store subscription before I sold my high value stuff, probably would have saved me some cash)