And they get it even if there are E- seats open further back. So just because someone is being put in E+ from the standby/"seat request" list, doesn't mean they're on a BE fare. Generally the assignment of BE seats is an automated process which will assign a BE customer to any open, unblocked E- seat (and I believe, unlike AA, BE is never put in an E+ seat automatically, GA has to do it after verifying there are no E- seats the customer can be put in). The other thing worth nothing, is BE customers can purchase E+ seats beginning at check in. So it is very well possible the "E+ upgrade" you're seeing a BE customer get it actually them paying for the seat.