I have no strong opinion either way, but your comment sounds a bit like "imagine they made saving lives illegal instead of murdering people" and then expecting us to agree with you.
France's high speed train network is powered by electricity which is primarily provided by it's nuclear energy power plants.
When viewing it through this lens then it becomes obvious trains have less climate impact.
If that is what you are optimising for then one is better than the other.
You have to choose some metric, this just seems to be the one they have chosen.
> If that is what you are optimising for then one is better than the other.
Yes, if the goal is to minimize climate impact at the expense of everything else, then this is logical, but that's not all that governments are supposed to care about.
If their analysis says something along the lines of "if we don't optimise for climate we all die" then I think it becomes pretty obvious what you optimise for.
However we don't have this information, we can only speculate.
Here are other than climate benefits:
Traffic is reduced in most cases (reducing infrastructure costs) (airports tend to not be in city center like train stations). Road use is decreased. Fuel imports are decreased. Noise and air pollution are decreased. Strike risks are likely decreased. Infrastructure costs at smaller airports is decreased.
Competition and end user costs are things that would be worse. (But France already have government granted monopolies for airports, trains, and airlines)
Not sure if you're trolling but a quick search finds that "rail travel accounts for 14 grams of CO2 emissions per passenger mile, which is dwarfed by the 285 grams generated by air travel, and the 158 grams per passenger miles from journeys in cars."