I know some pretty big companies that allow drinking during work hours. I'll name one that I'm not part of- Wells Fargo. You are not allowed to be drunk per se, but you are allowed to have a drink or two. I was surprised/shocked, when I first learned of this drinking policy in some companies, because it was contrary to what I thought was common sense about acceptable and unacceptable work behavior. I've since learned to accept that a drink or two is OK (in some companies- careful people), but being drunk is never ok. I guess it's kinda like- it's ok to drink before you drive as long as your within the legal limits.

Also most high level CEO's drink while on the job, simply because taking clients out to lunch, dinner, golf, whatever- so many drink as a way of building comradery or a close business relationship. Maybe that's how the whole "it's a ok to drink at work" (not be drunk), started for regular employees of these big companies too... I don't know, that last bit was conjecture on my part.