quicko: publishing banns

So it seems if you want to get married in Australia, it is a legal requirement that you publish your banns ahead of time. The traditional explanation seems to be that that would give a potential other spouse the opportunity to yell, "wait! he's already married to me!" The current explanation, though, is that it prevents Vegas-style weddings, thus rendering it legally impossible for an Australian to wake up accidentally married to, say, an American after a night of heavy drinking.