When I left Denver, squads of police were present in 'LoDo' the trendy part of town centre, at closing time every Friday and Saturday night, after several fatal shootings occurred following drunken arguments in bars and clubs.
So to say this is a UK problem is nonsense.
As for peeps showing up w/a hangover, well, like Paula said, better them than me.
I've got friends who drink and friends who don't.
If you're finding only people whose idea of fun is to go on the piss, branch out! Join a ramblers or runners club, get into some non-alcholic hobbies and you're likely to find similar-minded people who participate in a range of activities besides drinking.
Make it a positive, not a negative!