eBay

OP, have you talked to eBay?

Yes, I have talked with eBay and all they say is this is what they charge. No real explanation, other than that. 

"eBay didn’t charge a fee on shipping and the last time I bought something, they didn’t charge me a fee on the tax."

- that is because the seller pays the fees to eBay, not the buyer, unless it is embedded in the "Buy it now" price by the seller.

"15% is the price of admission to their vast buying audience and site logistics." - "overall eBay charge 15-16 percent fees and tax every item I sold " - " the sad part people don’t understand how  eBay charges both ways seller and buyer seller pay fees and tax buyer pay only tax"

- don't know where you all are getting this information, eBay charges 13.25% selling fee.

"No real explanation, other than that"

- why would you think they owe you an explanation? One either uses their business or doesn't.

you are right, doesn't seem right (forget 'fair', life's not fair)

ALSO, the tax was paid originally when the item was purchased. Is ain't fair that they keep getting tax, over and over, every time a used item is sold.

Your state's DRS (Department of Revenue Services) may have something to say about this. They regulate sales tax among other things.