Why is Xanax prescribed for anxiety by doctors, but alcohol is not prescribed by doctors?

Just to make it easier imagine a scenario where it is not called alcohol, but a more medical name like Alcax or something and the doctors said take 3 ounces of this three times a day. I don't really see the difference. Neither cures anxiety, but they both just calm you down for a few hours and have the side effect of drowsiness. In fact alcohol calms you down even more and unlike Xanax puts you in a pretty good mood.