> I am an immigrant here so not sure how common this is in Germany but I assumed that kids at this age usually are in school.
It’s very common actually. As you probably know, Germany has a three tiered school system where kids move to after finishing elementary school at circa 10 years old.
Going to school is mandatory for 9 years here, regardless of graduation or not. You’ll leave Mittelschule after grade 9, so at 15-16. Realschule/mittlere Reife is usually finished after 10 total years in school, so at age ~16. Meanwhile gymnasium takes 12-13 years (depends on the state, our schools are weird), so you’d regularly be finished at 17-18 years old.
iirc the distribution across those three tiers is relatively even on average. That would mean that most are finished with the primary education at 17 or younger.
> Also this is probably a "try it for a while" thing rather than the permanent / long-term lifestyle.
Absolutely. I’m a bit of a train nerd myself, but even I wouldn’t consider this lifestyle for much longer. But as long as it’s fun for him, I bet he’s DB‘s most reliable service tester