Might be a bit of exaggeration here.
Sounds like they could have used body filler and paint but the owner wants a whole new side panel instead in order to "maintain value".
I think its all about insurance.
I had my insurance company wanted to total my totally fine Q5 TDI after a minor accident. Their official line was that they were afraid a shop could not properly repair a diesel car, so it was cheaper for them to total (The actual repair cost estimate was less than their "totalled" payout). I had to argue with them for a few month to ensure title will remain clean after i said i will keep the car for a lesser (2/3) payout. Found a shop that repaired the damage (as i said it was minor) for about 1/2 of the sum i recieved and the car is still going strong (Getting close to 36 MPG for a powerful V6 diesel (with fully loaded car and loaded roof top box), around 42 with just myself.
But this was for a 2014 model (incident last year, so the car was almost 9 years old). I take it the Rivian owner wanted certified repair, so he had to pay the high price. Insurance companies are raising rates for everyone to accomodate EV owners unfortunately.