Bid Logs Support Legal Contracts
There needs to be some vetting process in place before a potential buyer can bid on any auctions. For some online auction platforms, that means ensuring that the buyer is a unique entity and not a shill. For others, the buyers may be required to provide proof that they are able to pay.
No matter the level of vetting you do, every buyer and seller will have to electronically sign your terms of service. In those terms will be verbiage that makes their bids legally binding—a contract—once they are the high bidder. Since legalities are now involved, bid logs become evidence in all types of auctions that a buyer did indeed make a particular bid.
Choosing whether or not to seek legal action will often depend on the size of the transaction and the demands of the seller. Not all negligent bidders will be taken to court, but you can take action against them by banning them from your platform if necessary.