Insurance companies and auto auctions are usually in charge of them. The goal is usually to sell used cars that have been repossessed but have few to no issues.
Buying a used car at an auto auction is generally less expensive than doing so privately or through a dealer. When you buy a car at an auction, as opposed to when you buy from a dealer, you essentially buy it without any add-on value.
A car may not sell on that specific lot for a variety of reasons. Perhaps the dealer already has an excess of that model on hand, which explains why it is selling slowly. As a result, the wholesale auction is set to take place. After that, a second dealer will buy it and take it to a market where they believe it will sell.