Putting unnecessary hardware in cars may be costly, which is why traditional car companies don't do this, or at least rarely do this. At the same time Tesla do

Putting unnecessary hardware in cars may be costly, which is why traditional car companies don't do this, or at least rarely do this. At the same time Tesla doesn't produce enough cars to make it worthwhile to make the production process that flexible. There are costs associated with having different parts to manage and streamlining your assembly line to handle it. Additionally you have to develop, test, produce these additional parts which also costs money. If they become one of the big car manufacturers at some point it will become worth it to specialize the hardware more. Right now software is easier and cheaper.