High-speed trains no longer make sense in the United States or Canada because in the last 100 years we've wholesale abandoned the infrastructure that makes them accessible, driven (literally) by the Big 3 automakers and Big Oil, who've had everything to gain from the death of rail transport. -Go digging up the history of the PCC streetcar conspiracies in the 1920s and 30s to see how diesel-powered buses and OWNING YOUR OWN CAR replaced clean, quiet electric trolleys.
In the UK things slid downhill this way for years under the nationalized British Rail, but in most of Western Europe and especially the shining example of train culture, Japan this isn't the case. Unless you're in a very rural area, you're never more than a few miles from the nearest local train station with decent service. And in the case of France or Japan, that leads you (probably within a half-hour's ride) to a high-speed, cross-country link.
That kind of convenience can't be rebuilt in today's economy and society- it has to have been ingrained in the public's interest and concern, and the space for infrastructure grandfathered from 50 to 100 years ago.