I read somewhere that the reason they don't typically use IT networking cables / tech is because normal IT infrastructure is a lot less strict with things like packet loss. It's actually not a huge deal to drop packets here and there, especially if any given component is at capacity. But in a car, some devices are super chatty and you can't be dropping packets much at all.

That said, I'm sure there's gotta be a better way to solve it with less copper. And I think they did something like that with CyberTruck.