I just can't say I agree with this statement. NYC itself being part of an even bigger nation-state should mean that a number of the responsibilities that fall under the purview of your example similarly sized nation-states militaries/establishments are likewise handled by NYC's parent state, allowing for efficiencies that free up resources better spent on other programs. On its face the duplication of effort on several levels seems wasteful.

E: So my thesis is that I agree that NYC should have the resources of similarly-sized nation-states, however they could be better apportioned.

By $ it seems almost certainly; by capability perhaps not.