Tiles are great, I’d love to have a roof last 100 years. But they don’t get as much use here because of issues with ice damning up the bottom edge and pooling water up under the tile, which then freezes and expands and dislodges or damags the tile. That can be overcome, but it’s easier and cheaper to use shingles.
There is a vaccine for chickens and turkeys for the bird flu. But poultry barns only use it when there are already outbreaks in their area, they don’t consider the cost worth it most of the time. And no one is giving it to wild birds.