> It's traffic that is completely below ground which means that no streets above are burdened with it, it's all electric so no emissions

So are modern subways. Cost is a major point tho, subways are designed to move waaaaay more than 30k people a day for much less, but costs of building are much higher.

This is only 1.7 miles and a novelty, I would not know If the differences hold for Tesla on other places or when scaling up. My suspicious is that it does not.

I also wonder that if you use the same tunnel they did but modify the cars to run by themselves using traditional techniques, would the operation get cheaper but the shortcomings be more glaring.