It's not really the flexible thing you picture with the word "loom."
The place Tesla used this was for fixed rigid bus bars, notably the "cable" from the charge port to the battery.[0]
Previously they used traditional stranded copper. Now it's a solid aluminum conductor, wrapped in insulation and protected by an outer aluminum tube.
These are thick high voltage conductors. I'm sure Tesla did their homework on flex and fatigue.
As for resistance, this is why I mentioned conductivity-to-weight as being the critical metric. Copper is over 3x as dense, at 9.0 g/cm³ vs 2.7 g/cm³ for aluminum. It doesn't hurt that aluminum is cheaper and more abundant.
[0] https://m.youtube.com/watch?v=hY9cxyvUu6I&t=1115s