"The framers of the constitution knew human nature as well as we do. They too had lived in dangerous days; they too knew the suffocating influence of orthodoxy and standardized thought. They weighed the compulsions for restrained speech and thought against the abuses of liberty. They chose liberty." ~ Justice William O. Douglas
What "Non-essential" really means....
The gang leaders can't decide how to spend the loot, so they decide to "shut down" until they can work it out. Because of thier self-imposed hardship, it should be easy to see and understand what their priorities are.
They shut down the operation of parks, museums, arts, issuing grants, welfare checks, WIC cards, social services...
But not the DEA, ATF, EPA, FBI, CIA, DHS, TSA, or other alphabet agencies. So it seems anything to do with service is non-essential, and anything to do with enFORCEment must carry on at any cost.
The agencies that deal in violence are essential. The agencies that deal in service are not.
It seems these two rival gangs agree on quite a bit more than they let on.