It is based on the ingredients and difficulty - first of all, almost all if not ALL of the cooking red scrip items are normal items...where as ALL or almost all of the other jobs have to craft MASTER ONE STAR ITEMS. Those items often contain many, many more expensive crafted bits than the cooking recipes (from other jobs I might add, cooking makes almost all of there own stuff with no reliance on other job crafts) - seems more balanced to me - cooking was right with the amount of scrips and the other jobs were way, way less than they should have been for the base items involved to craft them.
