IMHO it's a shame. No taxes on fuel while train companies have to pay taxes on electricity.

Rail infrastructures are massively subsidised though. Apparently subsidies for rail in Germany were €17B in 2014.

Though a carbon offset tax would only increase ticket costs by around €2 per leg.

That depends on the tax amount, doesn't it?

The rough estimate of the amount of damage a tonne of CO2 released into the atmosphere causes is $196 (source: wikipedia).

A an economy class return flight from Munich to Barcelona (a typical night train distance) releases 0.45 tons of CO2 per passenger resulting in an additional cost of $88.2 (72.6€), 36.3€ per leg.

Damage costs != offsetting costs

Every extra tonne of CO2 does cost $196+ (I’ve seen credible estimates as high as $400), but through offsetting you could verifiably ensure that more tonnes are avoided for far less.

As a crude analogy, if there is an oil spill (causing $$$ of damage), it would still be cost effective to plug the next oil spill for $.

Don’t get me wrong, the ideal scenario would be to not cause the first oil spill at all (in this crude analogy), but given that this seems impossible in our society, an offsetting tax on plane tickets could be a highly cost effective lever instead.

At which price point for CO2? Current estimates of >70€ per ton could make a flight from London to Berlin about 10€ more expensive.

It's $20 in Canada (where a carbon tax exists) and that comes out to 12 euro

tl;dr

The simple matter is air travel is stupid convenient between any two points not directly connected or where the two points are far apart. Its faster by far on longer distances and scheduling is far more flexible.

... long way around

The cost structure that exist is because train transport suffers some serious disadvantages airlines are not stuck with. If you want to claim an externalized cost that may not be paid in full your only choice is fuel costs but understand only a little over half of rail in the EU is electric. Even with higher fuel taxes trains will be at a disadvantage as shown below.

Airline travel schedules, capacity, and routes, can be varied as needed. Trains are locked into sharing tracks, may have have service requirements, and as a result cannot vary their schedules by much if at all.

Airline travel can also add and drop destinations with ease. Trains obviously require connections to each point separately. Rail construction, maintenance, to include tracks and facilities, can rival or exceed air ports.

Trains have the additional cost of staffing requirements imposed by various governments along with capacity requirements that can be out of date.

Finally, while trains have the advantages of lower cost for the train and carriages adding routes is just terribly expensive and their environmental advantage is being eroded as other forms of ground transport move to electric and all bets are off once air can be done that way

I would assume (without much research) that this artsy due to government support for EADS/Airbus in competition with Boeing.

Also interesting: Lufthansa is the company which probably good biggest single Corona-support, yet, in Germany.

Nothing to do with the planes themselves. Basically Ryanair business practice forcing competitors to up their game resulted in an ultra-competitive slim margin industry.

On top of that many smaller cities actually paid airlines to fly to their muicipal airport. The idea that Brest would pay €2000 a day to fly 200 passengers from London to Brest, and those passengers would spend far more than €10 each in the local economy.

There's no particular reason they couldn't have paid for a subsidized train route to get the same volume of visitors.

Convenience? There's the Channel to cross so you have to go through Paris and Dover. A <1h flight becomes a 7+h train ride.

Of course, but that's just an argument for why planes will win, not why an airport-specific tourism subsidy helped planes win.

Lots of railway equipment (vehicles, signalling systems) is designed and manufactured in Europe, and obviously the construction and maintenance staff have to be, so I don't see why this decision would have been done for Airbus.

I think it's more likely to have been convenient for the politicians, who had incomes that fitted with taking weekend breaks to Paris or wherever, and good for their voters, on a holiday package to Greece.

Difference being that EADS is/was co-owned by different European governments and also serves defence purpose.

Further conjecture I heard that I'm repeating with no supporting evidence: it was partly a side effect the Cold War.

All the new airports built well outside cities meant that low cost airlines could offer flights to (near) a major city fairly cheaply, which in turn pulled down prices for the entire market.