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.