A small part of it is the aluminum body panels, I think. Aluminum body panels can be repaired, similar to steel, but requires additional training/different tools. The Model S and X are majority Aluminum, whereas the Model 3 is mostly steel with a rear aluminum subframe. Basically if you get in a fender bender you need to go to a specialty aluminum body shop, which don't exist in high quantities outside of south bay.

Anecdotally, my Tesla 3 costs the same to insure as my 2006 G35.

Just looked it up it’s $899 for the G35 and $913 per year for the Tesla.

It helps to not have had an accident or a ticket in over 10 years.

Same here - my insurance stayed exactly the same going from a 2010 Nissan Altima to a new Tesla Model 3.

Cost to repair and near absolute unavailability of non-OEM spare parts doesn't help.

It also seems like even moderate damage, which would NOT be a write off on an ICE vehicle, results in them totaling it because Tesla refuses to work on anything with even relatively insignificant damage (and they won't touch anything that has a salvage title, so never buy a used Tesla with a salvage title. Ever.).