It could be LA's fault, You're right. However it does show that putting in a public transportation system isn't like spreading magical fairy dust that solves the world's problems.
It's like saying: "The world would be so much better if everyone could just learn to juggle 9 balls." Not only is the premise that juggling saves the world problematic, but there's a huge barrier of entry just to prove it could work.
My analogy would be: "America would be so much better if everyone voted." It's not wrong, it's incomplete, we really want everyone to fully understand the issues and then vote. Likewise, a public transit system alone won't make a city better, but a well-planned and executed one will.
I don't think it's unreasonable to say that if Elon successfully revolutionizes boring technology, it might be better to use it on a really good public transit system. And it's an especially important conversation if his fully realized tunnel network would make a later subway system more difficult/impossible even if people wanted one.
It's like saying: "The world would be so much better if everyone could just learn to juggle 9 balls." Not only is the premise that juggling saves the world problematic, but there's a huge barrier of entry just to prove it could work.