It's very strange - but brilliant! :) It means we entertain a lot more than we could in the Uk when we supplied everything
You then can take exactly what you want, and are self-sufficient. Just getting drinks out from your Esky!
We do the same and take it in turns to buy pudding (usually cheesecake from the Cheesecake shop - yummo) or salads. the Aussies like bringing a platter of cheese too - nice idea I think.
It's all swings and roundabouts and works out very fairly. Trust the Aussies to sort it out! :)