Why are the airlines still flying out of New York?

I am baffled by the continuation of air travel between New York City and the rest of the country. At the moment, the greater New York area is at the center of the coronavirus crisis in the United States, and yet Kayak confirms that, even today, anyone from the city and its environs can get on a plane and travel almost anywhere within the United States. Why?

As I write, direct flights from Newark to Miami are going for $19 on Frontier and $29 on American Airlines. Given the seriousness of the pandemic — and the number of businesses that have been shuttered as a precaution — this seems downright bizarre. Why, one might reasonably ask, are airplanes not subject to the same social distancing rules as other commercial services? The crab shack on the beach near me is closed because the authorities in my county are worried that its customers may stand too closely together while waiting for their tacos. Is this not an equal risk in Basic Economy on United Airlines?

The federal government enjoys only limited powers — and it should enjoy only limited powers. But even my cramped reading of the Commerce Clause allows the authorities in Washington, D.C. to regulate commercial interstate air travel. President Trump threatened a federal quarantine the other day, and then, on the advice of his team, rescinded the threat. Given the legal questions at hand — and the fact that the national government simply does not have the resources to enforce such a rule — this was likely for the best; thinly tested though the relevant precedents may be, it is not at all obvious that the National Guard is allowed to prevent cars from crossing the state line between New York and Pennsylvania.