1 Take the Deutsche Bahn train from Hamburg to southern Germany, and rhe fun begins:
connection times as low as 5 minutes (keep dreaming its not Switzerland)
trains depart late, so connections can't be made
booked night train compartments not available, they forgot to add the needed wagons / or they are kaputt
filthy and totally overcrowded even in 1st (selling more tickets than seats, reserving seats for multiple parties)
and so on.

​​​​​​2. Be spontaneous and take a train for long distance, impossible! Prices are even higher than flying.

3. No entertainment on board for kids

4. Lackluster and for years the same food and beverages.

5. you arrive at most train stations in Europe and exit to something between a former train station and a crazy place full of questionable people, doing drugs and other weird stuff in public. And the smell at those train stations, wonderful
Makes you feel safe, yeah.

And so on.