Given that a helicopter at that speed is a clear hazard to anyone below it and will blow a person below it off their feet, and could easily be pushed around or into the ground at any time (sudden gusts of winds do happen, although I have no real experience with helicopters so I may be wrong on some specifics), that is through.

"the park" includes not only the ground, but also a certain area above the ground - otherwise someone riding a bike through the park wouldn't be in the park (as they are not touching the ground) but their bike would be. That would be absurd.

Ok. What about 20ft off the ground? 50? 100? 200? 350?

You see the issue, yah?

Let's say we imagine a dome over the park which is geometrically a convex hull that encloses all the tree tops. Everything in that dome is in the park.

Given that the whole point of the website and the discussion is the fuzziness that any such rule implies, I'm pretty sure they _do_ see the point, but decided to play the interpretation game anyway. What's your point?

Your list of altitudes didn’t go high enough to change the answer. ;) Drones (in the US and the UK) must be limited to 400ft/120m and are still considered “in” the airspace of the ground they’re over. Commercial aircraft flying at 35,000ft AGL are not considered to be in the airspace of a specific park or private property when over the U.S. (and most of the world, I suspect), but they are considered to be inside the country’s airspace, since park & private property airspace has a limited ceiling, but country airspace extends into space.

What if it's using antigravity technology or magic to hover instead, posing no threat to the people below due to wind.

Through, no question. If someone in the park is able to interact with it, you're in it.

What if it is a digital vehicle? If we're all wearing AR glasses, and can interact with it, is it there?

Depends on how you word the question. If you say the helicopter is flying 10 feet over the park, by the rules of this game it's objectively not a violation. If you say it's 10 feet above the ground inside the park, objectively a violation.

In the U.S., by FAA law, flying a helicopter 10 feet off the ground in a public park is both over the ground and through (or “in”) the park. There’s no either-or.