Probably because the regular boring car stuff is not even made by car companies anymore LMAO.
The steering racks are made by Bosch or maybe ZF. Brakes come from Brembo. ABS module and its software is Bosch aswell. same goes for brakebooster, EPS pumps, AC compressors, and airbag controllers. I think the only electronics Tesla develops and manufactures are EV power electronics, infotainment, ADAS&Co and the drive motors.
If you take a VW Golf, you'll find the ECU and all of the software running the car is built by Bosch too. Essentially they sell VW a kit which needs to be mounted on a vehicle platform. Tesla is likely one of the only companies for better or worse that don't follow this model.
