Underage is taken very seriously and without knowing the details it wouldn't surprise me if BA was caught in a sting. Around here LEO frequently sends obviously underage kids into stores to buy booze; if you don't card and refuse them, congrats, your store is fined and you're surely fired.

However, the entire other myriad of liquor law peculiarities is ripe for the picking with violations (that I see) near daily, yet I've never heard of a charge on any other cause for retailers. If someone can somehow show that e.g. the state of MI has never in its history gone after an establishment for breaking the one-drink rule, odds are the DTW SkyClub isn't going to be their first.