Comment by ksec

Precisely this. Most people are focusing on the wrong issues, whether it should be tunnelling cars and not Subway trains etc. That is like arguing SpaceX is putting humans on Rocket and not Satellite.

If Elon could make tunnelling 10x faster, requires much less Human labour and reusable, this will dramatically cut down the cost of building SubWay, or other underground Networks. I am not sure if such tech could be used to build like a underground Shopping Mall in Cities. But if we could build a Walk way under every Car Road would be great for urban cities.