I do not know of a commercial airport without a train station. There do however appear to be plenty of rail stations that do not have airports.
>you can't (easily) take a train to a destination outside EU.
Britain is about to test this theory. But also, that is nonsense. Passenger trains leave and enter the EU all the time.
I went to a business trip from AMS (Schiphol) to WRO (Wroclaw). Wroclaw airport does not have any rail station (the nearest is a kilometer away). We had to take the shuttle bus to the train station in Wroclaw city centre.
The train from AMS would probably have taken over a day. Excluding check-in and luggage drop-off, flying took less than two hours.
Could you contact me when I would be able to buy a Paris-Tunis train ticket, please?