Cars are made with stamping presses and assembly lines; you also need a foundry to cast the engine blocks. All these things are expensive and take quite a while to set up.
OTOH, pick and place machines are fairly cheap and can be installed quickly; the R&D to make a phone is huge, but once you're done you can set up production almost anywhere in relatively little time. Obviously it'll be easier if you're close to your PCB and plastic suppliers.
Apple are using precision optics to select the parts with the right machining tolerances to fit together to minimise interface issues. Those parts are machined to very tight tolerances in comparison to a car.
I feel like you're trivialising the complexities of a phone production line.
No, I'm just saying that large-scale car factories are bigger, louder and takes up more space than consumer electronics factories. Apple does invest quite a bit in its production facilities, but most other manufacturers of consumer electronics don't.
OTOH, pick and place machines are fairly cheap and can be installed quickly; the R&D to make a phone is huge, but once you're done you can set up production almost anywhere in relatively little time. Obviously it'll be easier if you're close to your PCB and plastic suppliers.