If an ICE is, say, 15 minutes late, they cannot just drive faster to catch up. The schedule went on, and at that point there may be a much slower regional or intercity train on the same trajectory.
This is why ICE delays tend to cascade. It starts with a short delay, the ICE gets stuck behind a slower train, increasing the delay, etc.
The solution is better maintenance of tracks and trains, adding more rail capacity, adding redundancy, etc.
Of course, these are all much more expensive than an ICE speed experiment for PR.
Switzerland SBB/CFF and the German DB can not be compared, not even from far.
The Swiss trains are amongst the best in the world in term on punctuality. Delays barely exceed few minutes most of the time. Every connection is scheduled to be done < 5min. The usage is smooth like butter and It works like a Swiss clock.
At the opposite, German trains in the eastern part are barely on time and give you an almost Soviet experience for the regional one: The trains are old, poorly maintained, like the track itself and the service suffers of it.
The only place in Western Europe I experienced train to be worst than in Germany is currently in Hungary where there were actual soviet trains.
Even the freaking French SNCF with their legendary strikes tend to be more punctual than the DB.
As someone from the region, since when is Hungary 'Western' Europe? We are happy when acknowledged as 'Central' but this is new to me.