Australian standard circuits have 240V 20A <span style="text-decoration: underline;">wiring</span>, but individual standard power outlets are limited to 10A max by law. Standard appliances are limited to 10A max (that's 2400W). You can also get 15 A appliances, but they have a special plug/socket (taller Earth pin) and the outlet should be a single socket only in homes, though twin 15A outlets do exist in commercial/industrial locations.
It is not particularly heavy duty wiring - in fact a 240V 10A circuit will be lighter wiring than a 120V 15A circuit in the USA. Doubling the voltage halves the current for the same wattage, and voltage drop decreases with higher voltage because the current is lower - so the 240V system is more efficient than a 120V system for the same loads - thinner wires and lower voltage drop losses.