E.g. people commonly compare cheap plane tickets to the "regular" train ticket price, not to a savers ticket (which is bound to a specific train) booked early, which is more comparable to how you typically book a plane ticket. Similarly, the rebate cards quickly can make sense if you're not only traveling once. On the other hand, it certainly does happen that you can find cheap plane tickets on a connection where the cheap train tickets are already gone.
Time also depends, e.g. on where you're going in the destination town etc. If you take into account time to go to the airport, waiting and security time there, time to get from the airport into the city, ..., the train often isn't that much worse than it appears at first. Especially since e.g. a 6 hour train ride means I can sit down for 6 hours and work or nap, whereas the plane alternative is lots of short trips/wait times, which I personally find more stressful. I've flown inside Germany, but think it only makes sense in exceptional cases or if it's making a connection to an international flight.
In my case I compared all options on the same day, with a couple of months' notice - plane still cheaper. I take your point though about "hidden" time costs. I'm taking a bus for a future trip because, despite being significantly longer than the alternative, it's over 3x cheaper and - as you said - I can just (try to) sleep on it.
E.g. people commonly compare cheap plane tickets to the "regular" train ticket price, not to a savers ticket (which is bound to a specific train) booked early, which is more comparable to how you typically book a plane ticket. Similarly, the rebate cards quickly can make sense if you're not only traveling once. On the other hand, it certainly does happen that you can find cheap plane tickets on a connection where the cheap train tickets are already gone.
Time also depends, e.g. on where you're going in the destination town etc. If you take into account time to go to the airport, waiting and security time there, time to get from the airport into the city, ..., the train often isn't that much worse than it appears at first. Especially since e.g. a 6 hour train ride means I can sit down for 6 hours and work or nap, whereas the plane alternative is lots of short trips/wait times, which I personally find more stressful. I've flown inside Germany, but think it only makes sense in exceptional cases or if it's making a connection to an international flight.