Certainly the bid process could create a legally binding contract. The problem is getting that enforced. Hiring an attorney, litigating this matter, and then enforcing any judgment takes money, which I could certainly see any potential savings on the cheap price won in the auction evaporate. The dealers know this - that these situations aren't likely to actually be litigated - so they just move on forward and assume problem people go away.
2009 E93 M3 | Alpine White | Novillo Black | 6MT | ZPP | ZCW | ZTP | 19s | Premium Audio | Sirius | BMW Performance Exhaust