For every train, there is a fixed number of tickets per price category. So sometimes, you can still find cheap tickets ("super sparpreis") a day before because thag specific train didn't have many bookings:)
I worked in Germany in 2005 and back then everything was fixed price per kilometer for each train class, and you could get rail passes of sorts and get on whatever the hell trains you want during their validity. I'd take train roundtrips after work just to watch sunsets.
Surge pricing is not an uniquely american concept.
Railway systems with flat pricing and no stupid games are such a relief.