Bringing this thread back up - I am seeing the same behavior on UA and LH, where the flight is showing $50 more per person for the same booking elsewhere. Additionally, they are showing a discounted price for AS and DL (sometimes) when using MR redemption, compared to cash purchase. No price difference for B6.
This is definitely airline dependent. I also noticed that Amex randomly put AS and HA logos on its most recent spam promotion.