Related, but not quite the same...
Anyone know why BA/BMI (on domestic legs) only require your FF card to check-in and then don't require anything more than your boarding card at the gate, whilst all other carriers (EZ/BE/WW) require photographic ID when checking in and when boarding? I politely/in passing put this to someone at check-in last year (I wasn't in a rush and there was no queue) and they had no idea.
Answers on a postcard?