I think you may be confusing Android Auto with Android for Cars. The former is the mobile app and headunit-only integration (audio controls) via video stream, which requires minimal integration with the vehicle. The other is Android repurposed for headunits, with full car integration, such as Volvo's integration.
Car manufacturers of luxury cars shy away from Android Auto partially because they believe it turns one of their main selling points and silos (advanced technology) into yet another commodity.
Car manufacturers of luxury cars shy away from Android Auto partially because they believe it turns one of their main selling points and silos (advanced technology) into yet another commodity.