Originally Posted by thijsseh

The fare bucket will almost certainly be on the manifest (the printed list of passengers), so they will know who is on an award / upgrade and who has paid for the seat with cash.
There is also the information they have on their tablet, at least for J and F passengers as well as for silver, gold and plat Skywards members. There they have your stated preferences (from your profile) and - as far as I understand - also notes that have been entered by flight attendants on previous flights. Whether or not the fare bucket information is there as well, I don’t know.