That's what stucco is: Cheaper than wood siding and completely fire-proof. People just build with flammable stuff because it looks nicer. Stucco is cheap. Fire shutters are cheap. Composition singles are cheaper than wood shakes. Fine metal screens on all your vents costs next to nothing.

The ONLY reason the Camp fire burned the whole town of Paradise is they built with wood, they built too close together, and they had flammable vegetation too close to their houses. Lots of trees were left unburned, but embers from structures ignited shake roofs downwind. The medical staff and patients actually survived by moving into a fire-proof house!