Why doesn't eBay provide better ways for buyers to increase the belief of sellers that they will follow-thru on their obligations? I'm thinking of something al

Why doesn't eBay provide better ways for buyers to increase the belief of sellers that they will follow-thru on their obligations? I'm thinking of something along the lines of "earnest money" requirements common for real estate transactions. Could eBay require buyers to put 10% of their maximum bid in escrow via Paypal? If a buyer flaked out, he would lose his 10% to the seller as compensation for the time wasted. To implement such a scheme, eBay could at first offer sellers the opportunity to discount items won by buyers who made escrow deposits. Those buyers who didn't want to play along could bid as they do today albeit at an economic disadvantage. Eventually, eBay could allow sellers to require escrow. Even as a buyer, I would be happier if escrow was required because I would be less worried about shill bidders and others who run-up prices with no intention of paying. Of course, this scheme requires that all parties trust eBay/Paypal to act responsibly -- something the comments in this thread suggest is far from a given.