Why are non-essential passenger flights still being flown? I'm not asking about essential passenger flights like for "like food, supplies, and flying medical workers.

Oughtn't non-essential passenger flights have been shut down in North America, to curb the spread of COVID19? Have they truly not been grounded because 


  The airlines wrote to Congress that they’d lose an additional \$7-$10 billion if there was a mandate airline shutdown.


and airlines are "afraid of losing routes and more money"?
As discussed in this question airplanes carry a lot more than just passengers so shutting down passenger flights can stop the flow of essential supplies as well as people. In some cases charter flights are being used during this crisis but the general movement of people (even essential people) often relies on commercial flights. 

Similarly most states are issuing-shelter-in-place and stay-home-orders while it is only the federal government via the FAA that can totally shut down the airspace. Individual states, municipalities and private owners can shut down airports that they control but this may only stop flights in and out of those airports. 

Its worth noting that airports in other countries are starting to shut down. It is more than likely flights will be seriously curbed as a result.