Are the lack of visible spawns in your screenshot due to how far away you are from the park, though?
I live roughly 2.5 to 3 blocks away from a park, and I can’t see what’s under the Event Drops whatsoever. When I’m within a block and a half or so, then the spawns become visible. Similarly, @Ofzefishbone is already in a designated “park area” with lots of Event drops, “illuminating” all the nearby Event drops and showing what’s beneath them.
It might be a mechanic to prevent players from checking Event drops at a distance, forcing them to walk farther and get closer for a better look. But yeah, it would be nice if some areas were as packed with Event drops as that location.