There’s “parts built wherever” and “where the vehicle is finally assembled - from sub-assemblies”. I know of one specific vehicle OEM that had to place orders with over 2000 vendors once a vehicle launch was “a go”. Modern vehicles are massively complex, everything from the engine and transmissions to the infotainment systems. They’re quite amazing tbh.
Later that winter, I broke the clutch cable. I bought another cable tensioner and some bailing wire and used that to connect the clutch peddle to the transmission. I drove it like that for years. LOL.
I guess I like my modern vehicles but I sure do miss those simple vehicles.