These are not serious bidders. They are robo-applications or blindly copy/pasted applications by cut-rate shops that are mind-numbingly bad at development.
Are there really folks who run bots to scrape Elance, put in a bid for the minimum budget price (someone did bid $750, according to the min/max spread on there), and hope they get picked?
What happens when they do get picked, and they just agreed to build Amazon for $750? At that point I guess $750 is just so low an amount that neither party really cares to fight over it when the "developer" can't deliver?
But yeah, if you can get real work then run far far away. It is the proverbial shallow money trench where good developers die like dogs (only without money or that many good developers)