Coogee is in Sydney, where I live - about 30 minutes away, and my cousin lives there. He was over at my place on Christmas Day and said the beach was "going off" when he left. Failure in planning - you can't host a zillion backpackers over Christmas at our beaches and not expect a mess and/or a party. We're all very happy when they spend their money in the local economy for the rest of the time - this was entirely predictable and, with a bit of thought, relatively easily controlled.
Sydney will have an actual million plus people out and about to check the fireworks on NYE, in dozens of locations all over the city, and there will be a mess, and there will be parties, and by about 9am the next day there'll be no signs of it because an army of cleaners will start at 1am to clean it up. We're actually good at this sort of stuff as that's the nature of the city - there are large outdoor events all the time. This Coogee debacle just wasn't planned for correctly.
Yeah, you'd think that somebody with foresight would have thought to position a whole bunch of extra dumpsters at regular intervals along the beach and encouraged people to throw their trash in-- although then I suppose the regular beach-goers would have complained about all of the dumpsters. In a case like this there's usually plenty of blame to go around, not to mention plenty of fingering-pointing. But regardless of who's at fault, the end result is the same-- no more alcohol at the beach nice things.