So a car five times the price costs 50% more to insure??
That's not how insurance works.
Easy Counterpoint: The Land Rover costs only 15% less, and yet insurance is 50% less. Teslas are a ripoff. QED.
Actual car repair costs are dwarfed by the medical component, injuries, hospital bills, etc. Which somewhat plateau across all makes and models. There's a medical baseline that represents a large component of the necessary premium. This means differences between vehicles are even larger than they seem, because the first, oh, suppose $500 (made up, just for illustration) is medical. So now an $1100 vs. $1700 isn't 54%, it's ($1100-500) $600 vs. ($1700-500) $1200. A full 100% difference of the component from the actual car type.
This study was an average of existing insurance prices of real drivers for those vehicles, not a baseline cost for an equivalent driver across all vehicles. So these numbers include some selection bias.
The way that this would make a difference is, suppose drivers with a poorer driving history are attracted to Teslas. Then this method of sampling would show them higher than another similarly priced vehicle, even if same driver in each would pay the same amount (fictional scenario we have no info about).
Another component might be that Teslas are attractive to rich people who don't care about their price of their premiums because cost isn't an issue to them. They might not be poor drivers in a crash sense, but poor drivers in a demerits sense, that they don't care how many speeding/etc tickets they accumulate because, it's only money and they're rich, who cares. If Tesla drivers are less scared about the insurance impact of demerits on their license, their premiums will be higher. This is not true of a random person promoted into a Tesla, and thus their premium might not reflect so large an increase.
However, being blind to this, the reverse could just as likely be true...
Perhaps Teslas are attractive to people who're never on the road or who drive like grannies, never get into crashes, always run a clean license, (like, say, stereotypical Prius drivers) and these (high) premiums represent a huge discount to what some normal or average driver would be charged. Maybe it should actually be $2200.
Another thing to consider is that the actuarial models used by the underwriters can be increasingly competitive (closer to cost) the more accurate they are. The more data they have, the more accurate those models can be. Any type of unknown or uncertainty causes a spike in premiums so the insurance company doesn't lose their shirt if they guess wrong.
Supply chain uncertainty? Repair uncertainty? Driver uncertainty? All make higher premiums just for the uncertainty itself, let alone the actual higher cost of those components.