It's the difference between just walking to the station whenever convenient and making an effort to time your arrival to the schedule. There is a big jump in UX

It's the difference between just walking to the station whenever convenient and making an effort to time your arrival to the schedule. There is a big jump in UX quality between stressing yourself about punctuality and not caring, because a train will come soon enough. And it's not just a subjective "good enough" thing where it's not worth optimizing the last few percent: even if you did want to perfectly optimize to the fraction of a second, you'd still want to include some buffer time for unpredictable delays on the way to the station. When the train interval isn't bigger than your buffer then all that synchronization effort is completely wasted. (PS: not related to your post, just a remark on the wider discussion: it's quite misleading to say "Germany" when referring to a service level that is pretty much exclusive to Berlin)