Japan's high-speed trains are very impressive, departing some stations on a 12-minute interval, going 275 km/h and stopping only occasionally. Kyoto to Tokyo is what, 3 hours and there are 4 stops iirc.

But the trains go in all directions and are back-stopped by many local trains including express trains with inter-city service as well.

By contrast, a single dual-track system with only cars or nothing as a back-stop is not going to be reliable enough. What happens when a few days of repairs are needed on tunnels or bridges?

The other issue is political: does anyone think that Washington State is going to spend $50 billion on a transportation system in Boeing's back yard that is not made of airplanes?