afaik the ultra-cheap (free, .01, .08, etc) fares are usually on a basis of only one or two seats per plane at that price, and then it goes up to a much higher next fare stage. it's promotional material that says the fares exist (they do), they are just nearly impossible to get. the airlines do have to make money somehow! the ultra-cheap offerings are only a way to drive traffic to their website or booking system.