Trains are overbooked with free tickets and promotions (free pass for entire summer for 50 euro). While underlying infrastructure is not ready for such load. It leads to delays and mistakes. Plus railway stations in Germany look like homeless shelters!
On other side Germany has excellent motorway network. Flixbus is very cheap, quite comfortable, goes all the way to airport, and always on time!
Flixbus is 50€ cheaper when traveling that route tomorrow but that's about all it has going for it.
Planes? At least an hour, and if you cut into that, and the queues or security theatre more mind boggling than normal, you’ve missed your flights.
Eurostar is similar to airports, so I’m glowering at them too!
Doesn't distract from the point that long distances busses are very much not an alternative to rail (or planes for that matter) unless price is the deciding factor. And even the latter is questionable in many cases thanks to the 49€ ticket.