While I'm dubious about the linking of alcohol service to driving (especially before an international flight), I guess Qantas had to set its own guidelines and was wondering... 'what measure shall we use?'.
They came up with the BAC for driving and decided if you were able to drive a car, you should be able to board a plane and function in the event of an emergency.
Thinking about this, I suppose Qantas is covering itself in two ways:
- because F lounge service is by waiter, if the waiter served you too many drinks and you were later denied boarding, you could have an argument to blame Qantas. In the business class lounge, you serve your own drinks, so a denied boarding you'd have no one to blame but yourself.
- you might injure yourself somehow on the journey from the lounge to the aircraft. QF wants to avoid any claim on that basis.
There might be a third reason - although it's pretty thin me thinks.... perhaps QF is worried that in the unlikely event of an emergency, and your reflexes were impaired, you might point the finger at the service of alcohol in the lounge. Although that would somewhat be countered by the offer of pre-departure beverages by the cabin crew. I guess it might be feasible for lounge staff to notify cabin crew of passengers who have been refused drinks so the cabin crew does the same.