They are repossed or donated from what I understand.
Mostly it's auto-dealers who go, then they jack up the price when they sell them to you.
Kinda irks me a bit since I know a place I bought my current car (Titus will) goes there and I saw other cards similar to mine being sold for under 1k, yet they sold it to me for 4k. When I wanted to trade it in they wouldn't even offer me 1k in trade in value, and now I know why.
They were like, oh, we have to inspect it and there are fees etc.
Yeah, no, the reality is, they don't want to trade it for more then they could get another one at auction, and they are just trying to make as much profit as possible.