To be fair, when you compare LA-Seattle to Europe, the distance would be about the same as from here (Netherlands) to Spain. Which takes about half a day to a day and is just as expensive as a plane, but nobody does that shit. Plane's just too easy and you can get really low rates when you fly with something like Ryanair.
Where rail really shines is trips longer than an hour / one and a half (Intercity trains) and between really big cities (e.g. Brussels - London) as it provides a better and easier door-to-door time for people who need to be in the city's core anyway.