[Vespasian]

Exactly. The HW is pretty cheap but no HW is cheaper.

It has a ripple effect for other parts.

Button for everybody: More expensive and can't be sold as a package

Button optional: No Button -> Hole in plastic molded cover -> Either need different molds/parts or an additional preparation step removing the plastic covering the hole. Car manufacturing is traditionally very low margin business and extremely streamlined. Sooner or later EVs will also end up in the same situation