The problem with this logic is that an SF-LA line that serves nothing else actually fails to serve most of the state. The median Californian lives in Ventura, so if you just want to serve a majority you can do LA-SD and call it done. Or, you can do Bakersfield-Chico with a spur to SJ and Oakland, you’re also serving the majority of the state that way.
The latter is way easier to build in particular the spine through the Capitol.
> The problem with this logic is that an SF-LA line that serves nothing else actually fails to serve most of the state.
LA plus the Bay Area is most of the State, but travel between those two endpoints is a lot less than that plus travel between each of them and the Central Valley, and along the Central Valley’s North-South axis.
The latter is way easier to build in particular the spine through the Capitol.