I wish. Might have something to do with code availability dates and royalties given the timing of the charge to the customer. Digital pre-orders charge the customer at time of purchase, correct? Packaged pre-orders don't charge until ship. Pure guess, but I imagine there's something about the timing of these that complicates doing this kind of discount. I don't know though.
Well, on PSN, everything goes through immediately. It doesn't even hit the cart. Bam, you're done.
I'm not really sure how that'd work with Amazon. TBH, I've only looked at their codes a couple of times, and they were always full price, so I typically just buy directly on PSN. I did pounce on a couple of codes they sold over Black Friday though. In any case, I would assume they
could take pre-orders for codes, and just charge and deliver on launch day, but I've no idea if that's supported. I also assume they get
some margins on the codes which would in turn allow for them to discount, but they rarely seem to do that either. /shrug