there's no reason this system couldn't carry a bus.
musk markets to the elites first, then uses that to subsidize the mass market solutions.
And this reminds me of Musk's Hyperloop whitepaper, where he estimated it would cost 10 billion to run an evacuated tube from LA to SF, which was ridiculous. There's all this reality that he failed to factor in to his calculations, and once you've addressed the full costs relative to people moving capacity, all of the sudden Hyperloop doesn't look so great compared to conventional high speed rail, and his Boring concept starts looking more and more like conventional subway.
That avoids the need for big central stations (other than the ground-floor lobby, of course, but there's no way around that for a building -- a street transport system isn't limited to a single point of entry).
Express vs. Local was actually borrowed from that concept.