"EBay does not charge fees on taxes. They just collect the taxes from the Buyers, and pay them to IRS. They do charge fees on a whole transaction amount including shipping (taxes are not included)."
Incorrect on a few points.
"EBay does not charge fees on taxes." eBay charges the Final Value Fee as a percentage of the Total Amount Paid By the Buyer. The buyer pays sales tax on the purchase at the rate currently in effect at the address where the Thing will be delivered. Therefore, yes, eBay's fee is in fact charged on sales tax -- because sales tax is part of the Total Amount Paid By The Buyer.
If my buyer lives in Wilmington, Delaware, and wants his purchase sent to his home there, he pays no sales tax. If my buyer lives in Los Angeles, California, and wants her purchase sent to her home there, she will pay at least a 10% sales tax. WHY? Delaware has decided not to charge sales tax to their residents, whereas California and Los Angeles County, and possibly other governmental entities, has decided to charge sales tax at 10%.
Which leads to the second point of error: "They just collect the taxes from the Buyers, and pay them to IRS." Sales Taxes are paid to the various states, counties, water districts, waste management districts, whatever local governmental entities share in the revenues from sales taxes. Sales Taxes are not paid by eBay to the IRS which, of course, is the federal, national tax authority.
Which kind of circles on to the third point of error and also kind of picks up that first point of error: "They do charge fees on a whole transaction amount including shipping (taxes are not included)." Oh, yes, sales taxes are definitely included in the whole transaction amount. So, yes, taxes are a part of the total amount of the transaction upon which eBay calculates its percentage for Final Value Fees.
eBay's definition of the whole transaction amount, or the amount subject to the percentage for Final Value Fees include five things: (A) Price of the Item + (B) any sales tax + (C) the cost of postage or other shipping that the buyer chooses + (D) any handling charge that the seller might have included in the listing + (E) any other required charge, such as a state's recycling fees on electronics.
You are correct, however, about the early days of eBay when the Final Value Fee was charged on only the price of the item. (This was before South Dakota v Wayfair which made eBay a Marketplace Facilitator and required them to calculate, collect, and remit sales taxes to the various states.) Back in the beginning [note spelling], way too often sellers sold things like designer handbags for $5.00 with $300.00 shipping, paying eBay a percentage of only $5.00. eBay did crack down on that.
