[wongarsu]

The heat tiles are reusable, just like the Shuttle's. They are basically just a material that insulates very well, instead of a traditional ablative heat shield that burns away. With the space shuttle they ended up spending a lot of time inspecting each tile for damage and replacing cracked tiles. SpaceX has a modern iteration of the same material, hopefully with fewer cracks.

Other factors that work in SpaceX's favor are 1) that most launches will be unmanned, meaning they can take bigger risks than the Space Shuttle program; 2) that the steel body of Starship can handle higher temperatures than the Space Shuttle's aluminum, so a compromised heat shield is more tolerable; 3) for now they have a secondary ablative heat shield below the tiles (that does have to be replaced when it gets used, but that should only happen when tiles fall off)