The other one I heard of was similar -- someone went from an old beater car to a new Tesla. The old car only had liability coverage and no collision/comprehensive and they didn't change this when replacing the vehicle. They learned this the hard way when making a claim after a crash and having it denied.
I have to imagine this is the result of using a self-service portal from the insurance company. I gotta think that if you spoke to a live human at the insurance firm to make the change, they would not miss an opportunity to sell you additional coverage.
That abstract scenario aside, it's pretty bad that the insurance & dealership didn't flag anything in this issue when the Tesla was purchased. Even if they only gave a pro-forma "do you want to keep your current level of coverage?" It's bad... they're the experts on these things and should advise customers appropriately.