I've played at festivals in the UK, the US and Ireland and can't honestly make too many distinctions between them, culturally speaking. Except that in the US my experience was always positive in terms of sound crew and generally being taken care of as a performer. UK festivals are slowly catching on about ensuring performers have at least some cold water to drink - Priddy was great with a Green Room and home made cakes and tea!
As to dry or wet, there's far more of a tradition in the US for house concerts where there isn't always (or often, in my experience) any booze on hand, so not having much booze at a festival isn't a huge change. Yes, there's a beer stand at Old Songs, but only one, and even the Morris dancers were drinking more lemonade when I was there (twice). Personally when I'm performing I tend not to consume much alcohol, if any, so I don't miss it!
Anne