"Why do young people leave to go out at 11pm?? "
It's just the way things are these days most places are dead any earlier in Sydney. Anyway the new laws won't work because guess what happens when you lock out EVERYONE and stop serving drinks, they all end up drunk out on the streets at the same time which is where most of these incidents happen in the first place. Typical knee jerk reaction because of the wide spread media coverage.
