"It [the State] has taken on a vast mass of new duties and responsibilities; it has spread out its powers until they penetrate to every act of the citizen, however secret; it has begun to throw around its operations the high dignity and impeccability of a State religion; its agents become a separate and superior caste, with authority to bind and loose, and their thumbs in every pot. But it still remains, as it was in the beginning, the common enemy of all well-disposed, industrious and decent men." ~ H.L. Mencken
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.