Aluminium is very commonly used. It isn’t near as good a conductor as copper, but you can easilly use more toeget results and in most cases that works fine.

The reason we stopped using aluminimun more is it is relly tricky. when you tighten a screw the al deforms over time and so you don’t get a lasting connection. Al also corrodes to a non conductive state. Many house fires were traced to al wiring in just the few years it was common. We can mitigate all the above issuses but it takes care and so copper is preferred despite al being much cheaper.