I wonder what E-bay does to try and stop phishers from leaching off of their membership. Seems like a problem they would want to solve.
Gretchen and I recently used Ebay to sell some stuff and incurred the seller fees. Maybe we were ignorant. I just assumed that they would deduct form my paypal account automatically. Soon after our auctions we started getting phishing mails that looked like real ebay bills. The real bill also was delivered during this stretch, but we deleted it... on the assumption it was another scam mail.
So ebay lost out on payment from us for a couple of months until I signed in again and realized we owed them money. Doesn't sound like much, but if the story is common enough that's money they are losing out on.