You are making the assumption that it's one person traveling. If I imagine me traveling with my family, then the tradeoffs would look quite different:
1. There's only one driver in the car, so all other passengers could still work/read during the drive.
2. The cost is split. With three kids and two parents, the cost would be 45 EUR vs 50 EUR traveling with a somewhat fuel efficient car with an internal combustion engine. This is only fuel price and deprecation of the car is not accounted for and would be more.
3. The stress of switching trains multiple times with small kids, putting clothes on in the cold, making sure they don't bump into people, etc can totally negate any "you don't have to navigate traffic" benefits.
4. You usually don't travel from main railway station in city A to main railway station in city B. Getting to your actual destination can also be a slow and complicated affair with public transportation, especially in conjunction with 5.
5. Luggage can be problematic. If you are traveling with children, moving multiple heavy suitcases from one train to another while simultaneously taking care of kids can be a nightmare.