Quality of the rails makes a big difference, take the train from Ukraine to Poland and it's suddenly super smooth once you cross over into the EU
In BFE Texas or Utah or whatever the rails are like glass because crossing 300mi of nothing in 4hr instead of 8 has enough positive impact on the rest of the system that they deem it worth paying for.
It makes sense if you think about everything in terms of time between points.
https://en.wikipedia.org/wiki/Rail_speed_limits_in_the_Unite...
Europe is densely populated, you'll rarely see 300mi of nothing. High speed rail is still common. Only realistically limited by cost, not by the difficulty to get the train up to speed before the next curve, or other rail traffic, or grade crossings.
Freight trains carry heavy loads and have cars that are not inspected to have perfectly maintained wheels to the same level as trains that run on tracks for only passenger traffic, especially high speed rail (which runs on dedicated , highly engineered tracks).
The big reason that passenger rail, even overnight, isn't as economical in north america is because rather than sleeping on a train, it's cheaper and more reliable to just fly in a few hours across the country.
HSR makes sense in the dense US northeast or between Windsor and Quebec city in Canada (and probably California if it wasn't politically ruined with it's meandering lines), but sleeper trains for further distances would have to be dirt cheap to compete with flying. It'd essentially be for college kids or poorer people.
Most people who do long distance trains in North America are doing it as a cruise-like vacation/adventure.
Freight doesn't mean slow.
https://en.wikipedia.org/wiki/Rail_speed_limits_in_the_Unite...
That's a choice the country has made by subsidizing some kinds of transit more than others. Rail could be cheaper if we priced in externalities.
If alternatives get more expensive more people use rail, and the cost per rail rider drops.
At least in the US, people will tend to drive--perhaps shorter distances--if long distance travel gets too expensive.
All over the US, the tracks are being upgraded to 110mph standards. It just a slow process: 5 miles here, 20 miles there. Whenever they can find the money they do a new section. Every single grade crossing must be upgraded, every single curve regraded, etc. Amtrak can run at 90mph on those sections with the locomotives they currently have.
Sometimes they string together enough upgraded rail. Essentially everything in Michigan has been running 110mph for 10+ years, with the newer Siemens locomotives that can handle it. Also, the Texas Eagle and Lincoln Service - the entire time they are in Illinois they are running 110mph.
Upgrading 5 miles of rail doesn't make the news. That doesn't mean it didn't happen :)