International trains don't stop just anywhere so you still have to go to a big city to get such train.
If you want to go with train from east Germany to Amsterdam you still have to go to Berlin. It still takes ~6.5hr of train ride from Berlin to Amsterdam. Where flight is ~1.5hr - of course getting through security and all it is at least 2.5hr and then depending on which side of Berlin you live transfer from your place to the airport. Which I would say does not matter because for train you still have to get to Berlin HbF. You might have direct connection to Berlin HbF but as well some people might have direct connection by bus or train to the airport.
> Which I would say does not matter because for train you still have to get to Berlin HbF.
Most trains/ICEs will stop at 2-3 stations in Berlin. Usually they stop at least at Spandau and Hauptbahnhof, and sometimes Gesundbrunnen as well. You should be able to reach one of these stations in at most thirty minutes regardless of where you start.
All of these stations are major transport hubs and thus easy to reach.
Airports not so much: It takes me more than 90 minutes to reach BER[1], meaning I should probably depart from home at least 180 minutes before takeoff if I want to catch my plane most of the time. Note that it is usually recommended to arrive at the airport two hours prior to takeoff (or even three hours for international flights).
Following all the best practices and accounting for delays in public transport would mean I'd have to depart almost four hours prior to takeoff for a domestic flight.
To catch an ICE I usually depart from home about 40 minutes before it leaves Gesundbrunnen, which gives me enough time to grab some sandwiches at a bakery and a coffee that doesn't suck (DB is clearly taking their inspiration from airline food).
Heh. Funnily enough, My partner and I missed an FEX from Gesundbrunnen a couple of weeks ago (it's 3 stations from where we live). Because the transition time b/w S-bahn exit and FEX entry was 1 minute, clearly not enough time to find the correct platform and arrive there to board.
Of course, one guy was prepared and literally _ran_ to the FEX. We walked and then waited 30 mins for the next one to arrive. :)
If you want to go with train from east Germany to Amsterdam you still have to go to Berlin. It still takes ~6.5hr of train ride from Berlin to Amsterdam. Where flight is ~1.5hr - of course getting through security and all it is at least 2.5hr and then depending on which side of Berlin you live transfer from your place to the airport. Which I would say does not matter because for train you still have to get to Berlin HbF. You might have direct connection to Berlin HbF but as well some people might have direct connection by bus or train to the airport.