Adding to what folks have said, one of the single largest factors in Wildland fires destroying houses is the widespread use of tarpaper or shingle roofs. Wildfires in high winds launch large quantities of extremely hot embers and even chunks of burning materials, and generally the way these fires spreads to houses is those landing on roofs or vegetation next to houses. Less flammable roof options such as corrugated metal, slate or tile are significantly more expensive, so they are not used generally.