Earlier quoted context omitted.
No, it's not. Flying all those people on smaller planes would use far more fuel and cause more pollution.
Not flying would be best :)
My whole point here was to devise a taxation strategy to discourage passengers and airlines from flying short routes, and leave those to trains instead, reserving airplanes for the much longer routes where they're much less avoidable, and also to encourage more centralization of air travel from large cities and their airports, so that larger numbers of passengers are funneled onto a smaller number of very large jets for those intercontinental trips. Passengers would then just have to take trains to/from the smaller cities. Larger planes are far more efficient in terms of fuel per passenger per mile; much of the fuel burned in a flight is used on take-off and getting to altitude anyway, so maximizing distance and plane size means minimizing fuel per passenger-mile.