one legitimate explanation I have heard is that when a Tesla gets in an accident, even with minor damage, they have to replace the Battery, because they are not able to accurately assess the damage to battery and the risk of not changing it. This balloons the insurance cost.
This seems like a real public policy problem; a custodian in a Ford Escort should not incur an extra $20k in repair liability after a fender bender simply because the other car happened to be a wealthy lawyer's Tesla. At some point the owner of the glass car has to take responsibility for the risk of having it on the road.
That’s one possibility, but there’s also the well-known horror stories of dealing with Tesla service centers.