There are a lot of indirect subsidies going into air travel. To me this has always seemed rather perverse, and the money should have been invested in proper rail infrastructure instead, from a climate standpoint as well as for convenience (a proper rail network deposits you in the middle of a city without the need for a car, you don't have endless security controls etc.).

What indirect subsidies go into air travel that don't also apply to rail?

the TSA?

That's not really a subsidy for air travel, in fact it's a cost. People here are talking about how they would prefer rail so that they don't need to go through security at the airport. That's bad for airlines.

But who pays the TSA agents salaries? Buys the equipment?

To be fair, rail is also heavily subsidized, just in different ways.

(In Europe.)

Aircraft fuel isn't taxed, but train 'fuel' (electric or diesel) is taxed.

Airlines can base their staff in a cheap country and pay lower wages, avoid unions etc.

Local governments subsidise airports to attract tourists/business. The railway already exists and doesn't get this subsidy.

Local governments don't subsidize rail stations?