German car companies (or for what it's worth, everyone but Tesla) and their suppliers still operate in waterfall development. They never learned the lessons the software industry did, because (like other brands like Sony or Nintendo that are known for good hardware but bad software), they deem themselves hardware companies at the core as they haven't realized software is ruling the world.

Design something, ship it unchanged for three to four years, launch an incremental version, give another three to four years, ship a complete redesign. And that's not just valid for hardware but for software as well. Something like what Tesla does, changing stuff around whenever something is improving or they need to save money or whatever is completely antithetic to that.

Part of the reason is how Tesla operates: they manufacture everything they can in-house, the "dealerships" (=glorified showrooms) and service stations are all owned by Tesla. In contrast, the trad-car industry has soooo many layers with independent entities: the car manufacturers, their local sub-division fiefdoms, suppliers who are locked in with year-long contracts, brand-owned dealerships and service stations, independent dealerships and service stations... changes there take ages to be communicated across the field and become implemented. Tesla management, meanwhile, can just shoot off a weekly newsletter and everyone relevant now knows that starting from production date X there are only cameras but no ultrasound parking distance sensors, no matter the consequences.