I'm fascinated by the fact that my takeaway is the precise opposite of what the author intended. To me, the answer to all of the questions was crystal-clear. Yes, you can academically wonder whether an orbiting space station is a vehicle and whether it's in the park, but the obvious intent of the sign couldn't be clearer. Cars/trucks/motorcycles aren't allowed, and obviously police and ambulances (and fire trucks) do…
It isn't mentioned in the discussion on the results page, but one facet of effective moderation this shines a light on is as follows: each of us may find the moderation task easy, but few (or none) of us would be a moderator who would be universally trusted.