Why not both, as the meme says. The regulation is good because it directs consumer spending into the sustainable rail program. The fuel tax would also be good for its own reasons.
Suppose you think the environmental cost of flying between two cities is 100 euros more than taking a train. Then if someone prefers to fly even with a 100 euro carbon tax on flying, it is inefficient to prohibit him or her from doing so.
Only if the harm can and will be undone quickly with the collected tax.
But also, we prohibit lots acts that are harmful to others, instead of taxing them. It's also a moral thing. Values are changing and increasing share of people are seeing unnecessary emissions as a wrong.
Prohibition comes to mind. Not sure if the analogy works, but it does come to mind as something that I believe was a pretty inefficient ban where the impetus was likewise for the welfare of people.
Taxing liquor would have been a far better approach.
No, just that it was inefficient relative to taxing. Though tbh, I wonder why people who think taxing would be more efficient believe that. It seems like it would come with more bureaucratic inefficiencies and regulations trying to figure out how much to tax.
A clear well defined ban seems more efficient and straightforward, as long as it can be enforced. In this case - unlike for prohibition - it can be enforced like you point out.
They ban relative to what trains can provide and since French electricity emits few co2 it's quite and interesting thing to do. I agree on wors of "ban"chosen though. It's more of a market correction, in regards to AirFrance and SNCF (trains) being both government supported.
A single trip between Paris and Nantes is calculated (using some random website) to be between 0.1-0.3 tons of Co2 per person on the plane.
Using some other random website, the same trip for one person on train is calculated to be 2kg.
So that makes it a factor of about 100x. How much could the tax be that would still make it distinguishable from a ban? How would people react if say the tax would be 1€ per kg?