Why is it that AS makes me burn 40K Alaska Miles for a reward ticket to the Caribbean on American (when American only charges 30K AAdvantage Miles peak) - a 25% increase, when there's NO increase in mileage required were I to fly Delta (i.e. 30K AS Miles on a Delta -> Caribbean flight)? Delta only charges 30K Skymiles for a reward ticket to the Caribbean.

Make Sense???

I'd imagine there's something in the Partner Agreement requiring AS to charge more for those AA flights than AA charges their own AAdvantage members, but I'm wondering why??? Why not charge more for Delta flights than Delta does for its' own Skymile members?