The trouble in North America is that the railways are totally freight oriented. They have no interest whatsoever in passenger traffic. Whatever passenger traffic there is exists only because of government subsidies and government run railways and neither are all that interested in passenger traffic, which is not a recipe for development of a high speed passenger service.

 

High speed lines would probably have way different standards for grade and radius of curve, minimum distance of forward visibility, who knows what else. Worse if you need to run high voltage lines above the track where all the freight runs diesel electric.