Earlier quoted context omitted.
Because the amount anyone would actually pay is substantially below cost for most routes, but it's still a service that many people depend on (either directly or by the indirect economic impact of travel). It's a genuine force multiplier that is unaffordable without being subsidized; making it a utility would just shift the subsidy from credit card points programs to the government.
If airlines didn’t exist, people and goods would continue to move around the globe as they have done for thousands of years. There’s nothing magical about air travel (or any other transport mode) that makes it worthy of subsidy .
Indeed! We don't need air travel when we have perfectly good teams of oxen and covered wagons. We could even hunt and forage for our food along the way to save some money!