Hard but entirely relatable. Deutsche bahn is horrible, privatizing it in the 90s was one of many failures of that movement and was leading to crumbling infrastructure, an insurmountable hardware and technical debt and now to the most complex train system probably in the world. Hopefully some people learn from it - privatizing critical infrastructure like this is doomed to fail. You get the bad from a public company…
I consider it safe to assume that the reason for this is that it had been just the same when it was still a government org, but a government org will see its responsibilities very different from a company eagerly cosplaying shareholder-value while the sole shareholder happens to be the government they can freely rip off because of an ongoing legacy approach to the principal-agent problem.
As for delays, I think one reason, besides lack of maintenance and the massive interdependence in that large network that allows neither a star nor a main axis simplification is the high speed Autobahn: if they weren't overambitious in terms of travel times they would perhaps put bigger time buffers in their schedule and that would certainly help a lot.