1) Fuel tax. There's no tax on jet fuel, but rail companies pay tax on their diesel or electricity
2) Inflexible service, but high expectations. The European rail timetable is changed twice a year, and those trains will run (in normal circumstances). There will be a train from X→Y every hour from 5am until midnight, and those trains run even if very few people use them on a particular day. An airline can change the schedules more easily, and cancel/rebook passengers at fairly short notice.
3) Rail infrastructure is subsidized differently to aircraft infrastructure. I don't know enough to compare which benefits the most. Externalities aren't costed properly (e.g. noise and pollution).
4) Railways must still provide low-profit-(even loss)-making services, they may be expected to do this using profits from other routes. For example, long distance intercity trains might be subsidizing rural services.
More of an issue for lumbering freight trains than passenger trains though.
Answering your question, on the issue of price they note that no fuel tax is is paid on airplanes fuel and no VAT (21%) on flight tickets.
I think it’s a clever win/win play: reducing short haul flights in favour of railways not only reduces emissions and noise pollution, but it also frees up some capacity at Schiphol.
And there’s been some success already: the house has accepted a motion to eliminate the Schiphol-Brussels route.
By american standards, both methods are dirt cheap.
Ryanair cuts every cost you can imagine. No free water or pretzels, tiny seating area, no first class, outskirts airports, no checked or carry on, tarmac boarding.
On trains you get sufficient space to stretch your legs, a power outlet, wifi, unlimited baggage etc. and you get to arrive and depart in the city center.
I think the pricing is based upon consumer value more than service costs.
1. The discount airlines have become masters at turnaround times. When the planes are sitting at the gate, they're not making money. They slashed these as much as they could.
2. They only fly one model of airplane (typically either the 373 or a320) to simplify maintenance.
3. Most major airports in Europe are privatised. One of the effects of this is that they've become giant malls that want to get people through them, so landing fees have steadily gone down (there are edge cases where the airports pay the airlines to go to them, but those are rather rare exceptions).
4. Some airlines (more specifically Ryanair) fly to cheaper/more outlier airports. If you take a Ryanair flight to Paris, you're landing in Beauvais Airport, which is almost halfway to the english channel. You'll then have to take a bus. When in europe, I usually prefer Easyjet for the reason that though they're more expensive, you're landing at an airport with decent transit to the city you're visiting.
5. There's no frills at all. If you're just flying with no luggage, you won't believe how cheap it can be (I flew from madrid to london for 25 euros). But the fills aren't cheap. Checked baggage is more than the cost of the flight, food is a rip off, etc.
Also, trains in europe are still often state-owned (not the case everywhere, I know), so they're forced to run uneconomical lines for political purposes, etc.
Thing may have changed since a few things happened meanwhile, but a couple of years ago Ryanair got about 100 Million EUR [1] (sorry, link in Italian) from various Italian airports. Verona airport used to pay up to 24 EUR per passenger to low cost companies.
My understanding is that some airports have been opened for political reasons even when there was no real need, so they are "forced" to make such agreements in order to guarantee a decent amount of passengers.
I'm wondering if this happens also elsewhere in Europe.
[1] https://www.corriere.it/economia/17_marzo_18/cento-milioni-a...
As a european who moved to the US recently, this was mind boggeling the first time I boarded a plane in the US. I arrived at the airport expecting a typical 10 minute boarding time, but kept getting more surprised at how inefficient they managed to make boarding a plane as time passed. Just the time spend waiting in the plane at the gate before they let you get out seems to be longer in some cases than the typical turnaround time for euro flights.
Your statement that "As far as I know, for example, trains are significantly more fuel efficient per passenger-mile" definitely has some merit, but... trains are only more fuel efficient per passenger if they are as full as planes. An Airbus with 180 passengers might beat a train in per passenger miles if the train is not loaded.
Considering that, trains definitely are cheaper for highly utilized routes (commuting routes, for example), but for a leisurely trip across Europe, an Airbus packed to the gils could be cheaper.
The complicated area of railroad tracks probably doesn't help either. Someone is paying for them and the maintenance is frequent judging by the business my friends working on the railroads get.
And that's the catch. I've been told that years ago it was better, but try to catch a train to a secondary city in New England and you'll often find that the only offering is an occasional Amtrak branded bus.
I don't disagree that some other services might be alright, but that's clearly not one of them.