I was thinking some startup was a possibility. There’s obviously a ton of money to be made by making something go really fast. “Tesla sky teleport can get you from LA to Portland in 40 minutes.” Just sit in this cylinder as we launch you in your personal ballistic missile.

We saw a lot of recklessness with self driving vehicles. I wouldn’t be surprised to see a similar attitude while developing tech like this.

One idea that I've entertained is that they are terrestrial biological entities, like maybe a blue whale or giant squid but more rare and possibly of a shadow biome.