Cars being stolen to chop shops is a thing, I am extremely skeptical that it's the primary reason cars are stolen.\ -edit- Yeah even according to your source,

Cars being stolen to chop shops is a thing, I am extremely skeptical that it's the primary reason cars are stolen.\ -edit- Yeah even according to your source, a pretty tiny minority appear to be stolen for parts. Probably because, as you point out, parts are so easy and relatively cheap to get, except for inherently valuable parts like catalytic converters. And guess what? If people start stealing iPhones to harvest the gold/rare metals, parts pairing is not going to fix that.