The technology is interesting, but the trial of it should not be paid for by taxpayers. 
Elon has plenty of money of his own. Let him prove to us that it works and that investing public money will actually be worth it. It won't be. 
It would cost billions upon billions to build, and serve a very few people at a high price. It will never be an affordable option for the vast majority of us. 
It's a toy for the rich and they can pay for it themselves.