One of the problems is that the corridor in question is underserved in passenger rail right now. The only way to get between the two cities right now involves taking a train and a bus or two, because the rail company that owns the trackage between LA and Bakersfield doesn't want passenger trains running on it, and the rail company that owns the track between Ventura and San Jose would love to see passenger trains on that section of track halted as well. With such a hostile environment, it's difficult to build the interconnections that are needed for a modern rail system. Opening the Tehachapi Loop to passenger rail would be an alternative to a full passenger buildout, but you're never going to see BNSF agree to it.