I agree it is lunacy to demand a proof of age from a 50 year old man for an under age customer!!!!
Laws should be applied INTELLIGENTLY!!!!! Otherwise there is bound to be many indignant customers and LOSS of sales. All Duty Free stores NEED their sale volume to survive the high airport rents.
Just like I am now not stopped for age identification for entering into a club as the bouncer can clearly see I am no longer under the legal drinking age limit by many many years even with a youthful Asian face!
Enjoy your drink!