It's not about agility, it's about other manufacturers wanting a tried and tested chip design they know will last. Tesla is more willing to gamble, although they also removed radar from their cars to reduce the need for chips.
Is it the same reason other car manufacturers continue to use tiny shitty displays? I remember hearing similar arguments back then about that - the displays were 'hardened for cars' or something.
The simpler explanation is the other manufacturers can't adapt.
Radar was removed because the computer vision got to the point where the radar data was introducing noise and errors into the system - the quality of the sensor data went up after removing it. Karpathy's latest talk goes into this.
Let’s reevaluate in ten years, we’ll see how the legacy companies are doing then.