Hundreds of suppliers build components for the iPhone, and don't many suppliers build all the components for car manufacturers? Why can't Apple get these suppli

Hundreds of suppliers build components for the iPhone, and don't many suppliers build all the components for car manufacturers? Why can't Apple get these suppliers to make their seatbelts, airbags, etc? But maybe the game changes when using something like Gordon Murray's iStream manufacturing or how BMW is building the i3 & i8.