You're right, of course, which is probably why he's tweeting about it: once the public is sufficiently hyped about the hyperloop happening, it becomes harder for those governments to say no.
LA Metro is currently building a subway extension, and Beverly Hills has fought them every step of the way.
If you want this to happen fast, please let your local & federal elected representatives know. Makes a big difference if they hear from you. -@elonmusk [1]