In some country that kind of auction is considered gamble indeed and it's against the law (most EU as far as I know). From a Mechanism Design point of view, the

In some country that kind of auction is considered gamble indeed and it's against the law (most EU as far as I know). From a Mechanism Design point of view, they are maximizing their own profit and they also expect their players to be not very rational entities and so they don't nee to use a truthful auction.