The problem is a bit like a buffet at a cheap restaurant - you get the responsible ones who don't overload the plate and then you get the ones who go "bu@@er it, it's free" and walk back the Eiffel Tower on their plate....
Same situation here I imagine, except its grog and there's not a lot you can do to monitor it if its self serve unless someone is plainly out of their skull....
Oh well, be interesting to see what happens....