"Do count," the most obvious expense that comes to mind is that you can't use Central Park for free. As fof a few yearsa go at least, when I heard a number (since forgotten, sorry), but the City/Parks Dept charges a lot more than I would even consider outrageous, let alone fair (and that was just for a weekend 5-miler, when the park roads are closed anyway).
The roads in the park are open to traffic during weekdays. These would have to be closed for a Friday race. That takes cops.
For an Olympic Trial race they need crowd control and runner security (not an issue at, say, Club Champs). Even if no one shows up to watch they need these things...i.e., more cops.
And as you are proving, pains in the a-- are not just financial.