It depends on what metric you use. The US freight rail system is the envy of the world, for example.
The reality is that HSR isn't cost-effective if the trip takes more than about 5 hours. When you superimpose that time limit on the US, there's rather few viable HSR routes. A Chicago/NYC run is at that very margin of viability--and compared to most European countries, that's a longer trip than travelling from one border to another. It's quite easy to set up routes in UK or in Germany that hit all of the major cities in fairly short order, but that task is impossible in the US. Especially grating is the lack of collinearity between major cities; the Midwest in particular ends up having to be a star topology, since Chicago-X doesn't include multiple cities, and there's no route useful enough to be worth bypassing Chicago.