Given that I ski about 95% of the time in Austria, I can shed some light on this...
(Take into consideration that what I'm saying is observational-anecdotal. And there are many generalizations being made.)
As another poster mentioned, the legal definition of "drunk" while driving here has a much lower bar than in the U.S. In general, a single beer can put you over the limit. And while there is surely impairment even at less-than-legally drunk, someone having a beer or two at lunch, then slowly skiing down the pistes isn't a terrible public safety threat. I also think that the skiing and skill-set is quite different here than in the U.S. (most of my life has been spent skiing EC and WC... I'm from the U.S.). On any given day I see a higher average quality of skiing here than I do in the U.S.-- on piste. It's as if everyone here is a technically proficient skier, skiing pretty conservatively, making lots of turns. Of course there are beginners and reckless skiers, but I see the skill/conservativeness distribution here lumped up on the right side of the chart. At the same time I see fewer people on piste that make me think, "Damn, that person is great." But I chalk this up to i) many folks attaining a certain level of parallel ability and then feeling little desire to progress, ii) those that are incredible skiers here still seem to relish their technically perfect, but calm/moderate pace.
At lunch, the mountain gets empty. I eat on the gondola and keep going. Tons of one or two beer lunches, usually weissbier (proudly isotonic and touted as a sportsman's refueling drink here), followed by perhaps a run or two by a lot of the locals-- ending their day around 2pm. All in all, it seems skiing for the masses here is more calm recreation than an adrenaline junky's dream. After lunch the mountain stays relatively quite, with numbers rapidly dropping off. Many people head to one of the mountain's lower bars/restaurants, some a stone's throw from the base of the mountain of the gondola that covers the equivalent of the valley run... down to the bottom. Many people download via gondola.
Now, drunk drivers on the way HOME from the mountain might be a more serious issue here. The bottom of the valley run has about 5 super-crowded, ad-hoc, on-the-snow, open-air bars, blasting techno-oompah-schlager-shit, and general madness.