Why is it buildr are using aluminum over fiberglass? woudnt fiberglass be lighter then aluminum?

Im just thinking that fiberglass would be ligther and easier to mold then aluminum, but aluminum is faster but harder to mold. I think they both equal out in price going form the expensive aluminum sheats and then to the fiberglass resin, sandpaper, and bondo.

Make a million, use the glass.. Make twenty, use the aluminum.

We tried that and the fiberglass tends to crack, chip and break whereas the aluminum won't. I thought we were saving money until we had to redew half of the fiberglass in aluminum.

This ? should be in tech talk?
(sandrail tech)