(because if one or the other wins by spending 10x, well, duh)
I do hope part of the cos analysis is likely rent / housing costs paid by the commuters as a result of the build. I tend to think an extended range from higher speeds would decrease total housing costs but I too would want to see figures.
Of course it isn't clear how the hyperloop would work in practice, but I doubt a station would be less footprint than a train stop. And running the services simultaneously is probably harder with small shuttles than with a train that just stops at each station. Likely faster, but a lot more complicated.
"Sealed capsules carrying 28 passengers each that travel along the interior of the tube depart on average every 2 minutes from Los Angeles or San Francisco (up to every 30 seconds during peak usage hours)"
So, that's 28/pod, not 12. At 30 second intervals, that would be 56 passengers/minute or 3360/hour.
For trains, we have (https://en.wikipedia.org/wiki/Route_capacity#Route_capacitie...):
"Tram and light rail systems have in theory very high route capacities, but in practice route capacities of 12 trains per hour is a practical upper limit. For High Speed Rail a route capacity of up to 18 trains per hour may be possible. The Punggol metro line in Singapore uses a moving block system to achieve a headway of 90 seconds, so the route capacity is 40 trains per hour."
So, let's take 12 trains an hour. Then, each one would have to carry 280 passengers to be on par with the maximum mentioned by Musk. That's ballpark what https://en.wikipedia.org/wiki/R160_(New_York_City_Subway_car... delivers, but about a third of https://en.wikipedia.org/wiki/London_Underground_2009_Stock.
So, I think an optimistic view would say you need two hyperloop tubes to get capacity of a single subway rail line (optimistic because it rounds down train capacity, and accepts Musk's claim of 120 pods/hour)
High-speed train may be different, though. https://en.wikipedia.org/wiki/SNCF_TGV_Sud-Est has a capacity of 350, and https://en.wikipedia.org/wiki/Acela_Express#First-generation... about 300, both ballpark the top of Musk's claim.
On the other hand, https://en.wikipedia.org/wiki/British_Rail_Class_374, used on Eurostar, has 900 seats. So, I guess TGV and Acela use multiple carriages in a single train. That, again, would mean you need two hyperloop tubes for one train.