Imagine if DB went fully public again, and was entirely subsidized. So many other social welfare programs exist in Germany, why isn’t transport one of them anymore?

There are lots of smaller programs like Schülertickets, why not just make it universal?

Last year there was a brief period where the same ticket cost 9€/month. It was a success but discontinued for mainly political reasons. There is a fund however where you subscribe for 9€ and if you get caught riding without a ticket they pay your fine. Unfortunately, the threat of prison makes this idea not sustainable. But it is a nice display of hacker spirit.

That's misleading wording. The political reason for discontinuing was that it was started as a limited-time, limited-cost experiment.

I feel very strongly that states should be able to run limited-time, limited-cost experiment, even big expensive ones like this. That requires that people accept that the experiment ends, and do not expect it to be a new norm. If people expect an experiment to last forever, then it'll be too difficult to agree on what the next experiment may be.

Besides, I feel that it's stupid to think that the terms/rules which were chosen quickly for an experiment happen to be the best ones for the long-term future. If anyone says so, I think that implies that they haven't really studied what happened in the experiment.

While I generally agree with you, I think a lot of anger comes from the amount spent on cars (including for the Dienstwagenprivileg) and roads, versus how much is considered "too expensive" regarding public transport.

And Dienstwagenprivileg really is a privilege: it's usually only for people whose jobs involve a lot of driving (sales or consulting) or as a perk for managers.