high speed rail works in japan and to a certain extent, other smaller countries.
subway is also fantastic in big cities.
BUT i do not think bullet train will work in the US. and same goes for subways in some of the US cities. I like the subways in NYC, Boston, and DC, but the subway in st.louis feels ‘dead’.
It's a matter of population density. Some cities, some regions, some countries, have it. Most don't.
In 95% of the USA bullet trains and subways are square pegs trying to find a square hole.