Teslas are not aluminum monocoque. Thanks for playing.
Like all cars, they're made from a mix of metals. I can only assume that you're thinking of the gigacastings, which are deep interior components, and if you're damaging one beyond usage, you've utterly obliterated your car already. They're not crush structures; the crush structures are mounted to them. They're also not the only main structural elements. The pillars for example are UHSS (ultra-high strength steel). But you're generally not going to be replacing or welding UHSS either. Once again, Tesla is not at all unique in this regard.
And technically you could fix mangled gigacastings, with body pulling. But body pulling isn't recommended on any monocoque car, only body-on-frame, as force transfer in monocoques is unpredictable.
As for "impinging on battery components", again, the battery is nestled between the gigacastings, making it even more internal. If you're penetrating that deep into the car, you're already talking about a writeoff.
People seem to have these weird images in their head of cars that are utterly mangled just being fixed for a practical price. That doesn't happen. Cars have outer panels and crush structures that are designed to be repaired / replaced. If you're penetrating deeper than that into primary structural members, the insurance is just going to write the car off.
Lastly: I have a Tesla. There is no "high cost of insurance". It's perfectly reasonably priced for a car of its price.