Musk is proposing to make an expensive part, boring tunnels, cheaper. But then he also proposes a fundamentally boneheaded change that makes any improved efficiency there much worse: individual vehicles which are fundamentally unscalable.

So I wish he would keep the good part, cheaper tunnels, but not sabotage those tunnels with an unworkable vehicle proposal. It also gives a ton of power to the obstructionists to sabotage real transit projects and increase their costs, because they can say "let's try what Musk is proposing".