We have mechanisms for solving collective action problems. If air travel is bad and we want people to take trains, just tax airplanes and subsidize high speed r

We have mechanisms for solving collective action problems. If air travel is bad and we want people to take trains, just tax airplanes and subsidize high speed rail. I don't know how you expect people to pay twice the price and take twice the time to travel somewhere. Prices are information. Tax externalities.