Additionally, another downside I noticed when I was there was that around 2am in the summer, the streets are often flooded due to people watering their lawns. Besides the absent or poor pedestrian infrastructure, this made my after work walk quite a bit more complicated.
My electric bill is about $80 in the summer to keep my $125k, 2000 sqft house at 72F. Not too bad IMO.
And everyone (40% of the houses in my neighborhood?) who waters their lawn does so at dawn and dusk, not 2AM. If you water in the middle of the night when the grass is cold and dormant, you can get mold.
Air conditioning is mandatory some areas, with temperatures in Sydney peaking over 40 C (105 F) in the summer, and electricity costs 27 cents per kWh (US$0.20).
Australia has some of the most expensive electricity prices in the world, as Australia is completely incapable of managing its infrastructure properly.
You'll need a car, of course, and as long as you're not eating at trendy places downtown, everything else is pretty cheap. Bars have $1 beers and burgers at happy hour.