Those aren't the valuable parts though. With Teslas, the exterior parts (like the panels) are the most valuable, because those are the parts in shortest supply

Those aren't the valuable parts though. With Teslas, the exterior parts (like the panels) are the most valuable, because those are the parts in shortest supply for the kind of work that third-party repair shops can handle. If you have an issue with the battery, that's not something a third-party shop can handle.