An opinion piece by David Dayen does a thorough job of dismantling the fantasy that Elon Musk has discovered a solution to congestion. The headline of the article compares a transportation future designed by Musk to the lines at Disneyland. 

But first, you'd have to get your car into the tunnel. Musk's design fails to solve that fundamental challenge of all PRT systems — which is why practically none have been built. Worse, Musk wants to cripple the already gridlocked above-ground network, also known as roads, in service to his subterranean fantasy.

Then there's the obvious self-interest in the proposed network.

If the Loop has too few stops, the result is an inefficient, relatively useless subway. Musk's initial map of 60 miles of tunnels had only 23 stops and seemed to mainly be designed for his personal comfort. It conveniently includes his own commute from Bel-Air to Hawthorne, a few sports venues, a couple airports for when he has to fly, and pretty much nowhere that the bulk of the city lives or works.

Then comes a warning, couched in an appeal for expertise and collaboration to run the show:

This kind of boondoggle is what you get when a libertarian billionaire tries to solve a problem that requires collective action and shared rides.