Because Tesla is a car company. Literally, they only things they currently build are sedans, a crossover, and a handful of semi-developmental semis. They're b

Because Tesla is a car company. Literally, they only things they currently build are sedans, a crossover, and a handful of semi-developmental semis. They're building factories as fast as they can and still can't keep up with demand. Plus you have that corporate "synergy" with everybody using the self driving tech to produce more test data, although enclosed single lane tunnels populated only by self driving vehicles should be a trivial use case for it. In some ways using Teslas as the cars is nice. If the system is lightly loaded the waiting time is always short. There's no "waiting for the next train/bus to arrive". The downside is that if it gets busy the system doesn't scale well, maximum capacity is low, but that's a future problem and it is trivial for Tesla to swap out the cars with higher capacity vehicles once they are building them. One of the nice things is that the per-car cost is far lower than it is for a train car (which typically cost on the order of $2 million[1] each), and the cars can be sold on the secondary market to make back some of the capital costs. The secondary market for metro cars is far smaller. [1] https://wamu.org/story/20/02/27/metro-just-received-the-last-of-its-7000-series-rail-cars/ https://wamu.org/story/20/02/27/metro-just-received-the-last...