I think they’re trying to say that less people would fly than currently drive due to the cost of flying. Although, if we subsidized personal planes at the same rate that we do personal vehicles I’m not entirely sure that flying would continue to be so expensive.

It’s quite simple really. Less people would be able to fly, so those that can’t will just stand still in confusion until they die from starvation. The remaining population would be the small fraction who were able to afford to fly. Net loss in pollution.

Flying is expensive and you need a license that’s substantially harder to get than a driver’s license.