It turns out that what Bui did to his Laguna Beach house didn’t cost much.
He made sure that the roof vents wouldn’t allow embers into the attic space- this is a major way that houses catch fire, even when they have cement roof tile.
He built with minimal or no eaves- superheated air will collect under roof overhangs and ignite the structure there.
Any and all exposed wood was covered with a very thick coating of stucco- maybe an inch thick.
I don’t know if he did anything with shutters, but ‘fire shutters’ prevent radiant heat from igniting the inside of the house when the windows remain intact. Fire shutters would be an added expense to a house. The ember proof roof vents, minimal eaves, and stucco coating wood surfaces doesn’t add much at all.