Two wrongs don't make a right. If a particular taxpayer-funded road was one cent per mile for the end user as opposed to other higher-priced roads, you wouldn't say, "wow, this road is reasonably priced!" Unless you're literally just doing a travel blog

Is it a wrong?

There's a lot of externalities around transit that aren't directly priced into costs vs ticket revenue.

If France decides "We want high speed national rail connectivity between cities", I'd look at it more of an entitlement / service than a profitable enterprise.

Nobody expects national healthcare services to be profitable.

(Also, both France and Germany's relatively recent experience with their national rail networks being the reason their countries are still independent sovereign states)

They want it so much that they're unwilling to pay the actual cost of a ticket lol. They have to launder the money through an intermediary and offload the cost to people who don't use the train that everybody supposedly wants

Germany and France were on the verge of collapse or being conquered but government trains saved them? Do tell.

But also, they're maybe not very sovereign when a foreign body drafts, ratifies, and enforces their laws

That's the way all government services work.

Public libraries don't run as profit centers, and yet everyone generally agrees they provide a social benefit and are worth funding.

Ref: world wars, part I and II.

If everyone generally agreed that injecting messenger RNA into the eyeballs of infants provided a social benefit you would go along with it.

So you're saying that if the Nazis didn't have subsidized train rides for tourists they would not have been able to collapse the Soviet Union in 1991 and regain East Germany? Interesting. Very interesting, sir.