What?? In Europe there are lots of viable alternatives. Same as Asia!!
Once you include getting out of Stockholm to the airport, security, boarding, the flight itself, possible baggage collection, and the trip into Umeå, I would be surprised if the total were much below 4 hours. Comparable German domestic flights such as Hamburg–Munich usually took me around 4–4.5 hours in practice in the past when traveling for work before the pandemic.
That makes the train a 6–8 hour alternative to a roughly 4-hour flight journey. Whether that is viable depends on the traveller, but it is certainly more competitive than “1 hour versus 8 hours” suggests.
I admit that for me, living about an hour north of the Hamburg main station but only 15 minutes from the airport, the plance for a business trip in Munich can still be a viable (albeit seldom taken) option. More often than not, if time permits, I take the train, work on the train. But as said - there still are situations, that make flying such a distance viable (to me).
I just wanted to point out, that it is not as clear cut as 1 hour vs. 6 to 8 hours.
Of course there are a lot of variables, if instead I leave from my house the aircraft would actually be faster, mostly due to the extra time it takes to get to Central London and from Waterloo to Euston.
In reality we usually drive in about 6-8 hours because, as a family of 4 traveling, it's considerably cheaper even before you take into account having transport on the other end.
I and a friend once started at Stockholm Central station to Malmö Central Station at the same time. I boarded a bullet train; he took the bus to the airport ... We arrived at the same time six hours later.
I've been looking at travel in Japan recently. Between Hiroshima and Tokyo, the bullet train (fast Shinkansen) and flight are both about four hours.
A bullet train is much more comfortable than flight within these limits because there are so fewer steps: no travel to/from airport, fewer tickets to book and often no check-in or security checkpoint.
I think a lot of people do not understand just how massive the US is.
Sure some routes could have viable alternatives, but others just do not.
The thing is, a high speed corridor enabling that trip would, as you note, involve many stops of which each pairing represents another potential flight that the same train might replace. Many of those pairings will be short enough flights that a proper high speed rail corridor would easily compete with if not destroy the short-haul flight offerings.
To use your example, it looks like there are currently two flights between California and Maine, both run weekly by United between PWM and either LAX or SFO flying east on Saturday mornings and returning west on Sunday morning. A hypothetical high speed rail corridor connecting coast-to-coast between either of those city pairs might not replace a lot of flights across the whole country but one train running along that full route might have replaced one from Portland to Buffalo, another from Boston to Columbus, another from Cleveland to St. Louis, et cetera.
For rail? You're looking at an order of magnitude more for planning and construction, all new infrastructure, all new rail stock. It will take a much larger passenger base to justify the expense and effort.
Airplanes don't just shine for longer trips. There have been some interesting developments with commuter airplanes that are either all electric or hybrid with a 200-plus-mile range. If they are as energy efficient as they promise to be, we could see a resurgence in municipal airports for transportation between regional centers where rail is either unavailable or excessively expensive.
Some of those are amenable to high-speed variants, some less so. And once you've established transport corridors, much of the hard part (rights-of-way acquisition) is accomplished, so that adding a high-speed route becomes far more tractable.
For the most part, actual construction costs are fairly modest, modulo bridges and tunnels, both of which can of course be quite expensive.
I think increasing the viability of travel between smaller airports is a good thing for those times when you don't want to spend a lot of time traveling or waiting for a transit vehicle. If the equivalent of micromobility air travel comes to fruition, you'll see two- or three-person vehicles that get up and go when someone wants a ride. Another benefit could be the airport-to-airport delivery of packages with different-sized drone craft and autonomous navigation.
#IFoundMyFlyingCar