Too many internal and polarizing conflicts in United states society. 

When you consider how the society of the USA from the individual to the mass scale is nurtured...
Although there are positives and overall good nurture methods and actions. When you consider the amount of propaganda, non transparency, corruption, and human exploitation, gaslighting governing forces in the USA and nameable other countries...
This can be seen as a true solution to your question.  Because fast speed train development and implementation can easily be coordinated,  but with the lack of concern and coordination to achieve such a,now beyond easy, task because everyone is focused on themselves and mainstream issues...
The society in America is highly individualized and independant, this has many positives and cons. One con is that. Obvious mass societal beneficial actions/changes such as European/nordic advancements in equity and progress, and Japanese bullet train don't get implemented quickly if at all. 

Ofcourse there are more obvious responses, like what all it takes to build high speed trains like seen in Japan, the obstacles. And the past and current consequences and cons of bullet trains. But above all else. I believe it is beyond notable that the reason there isnt mass adoption of modern high speed transportation systems could be because of a mix of intentional and unintentional design. 

Few political and business self interests could be the 'king' of the nation. In America there were supposed to be no kings. But it can be said the dollar holds the crown, or that the crown is held by the rat race not the human race. So this leads to the overall exploitation and self neglect of the human race in various aspects and forms. 
When we sit back and think about how some country or parts of the world have more equity and perhaps percievable happiness or satisfaction of individual and their relation and self reflection of themselves to the governing body of the nation they are citizen to or reside in. When we think about that, it almost becomes a no brainer that these ideas, ways of living, and ways of governing should be more universal.
Instead of having people who are relatively uneducated or relatively unsuccessful or relatively unsatisfied with themselves and their relationship and reflections of them selves to the governing body of the country they reside in. America doesn't have it, because it sucks to suck. And maybe if we atleast embrace the such which we also don't do in America, maybe then we'll be harder on ourselves individually and at mass societal levels to actually make up for our societal cons or things we fall behind on.
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