You are still simply going with one glass of wine will affect everyone equally, and that is proven to be untrue. (Or stress, for that matter)
While your friend made a call judging their own abilities and the level of emergency, that's exactly how it should be: cars should not stop us humans for making that decision.
(Fwiw, if you were just having an alcoholic drink, a breathalizer would show a much higher concentration even though alcohol might not have even kicked in or there wasn't enough for it to kivk in at all)