despite the fact that the race stuff costs as much or more (lower quantity production, sandwich vs. cap, more metal). ...Want some proof? Look at the top list price skis for each manufacturer. For Volkl, it's the TigerShark with the Powerswitch. Atomic is tied between its various top tier hardpack skis - GS12, SX12, SXB5, and M:B5. Rossignol's top priced ski is (wait for it...) the R11 Mutix.
While it almost certainly was true at some point in the past, the new class of premium skis absolutely cost more to produce than a pair of race stock skis. These skis have constantly evolving shapes, binding system interfaces, constructions and gizmos - requiring new and more complicated (read: expensive) molds every year. Worse, these molds become obsolete when the new crop of premium models is introduced. Molds are one of the largest fixed costs in manufacturing skis.
In comparison, change comes more slowly to race stock ski production. Sidecuts and constructions don't change radically every year, allowing the manufacturer to use these sidewall/sandwich molds over a much longer period of time. Also, sidewall molds can be modified to make different sidecuts - cap molds generally can't. The mold cost gets ammortized over a much longer period of time, ultimately making the skis less expensive to "produce."