In any of the companies I've worked with or visited in my times in the US (SF, specifically), lunchtime drinking was pretty common, and practically unheard of in my European experience.

Like yourself, I wouldn't want to extrapolate a broader trend from that, just providing a counter-anecdote.

Think on smoking we've probably had a similar experience though. I don't think I even know an American that smokes (cigarettes), let alone seen it at a workplace. In Europe, it'd be weird if there weren't a couple of people in any office that didn't have an obvious habit.