[qnpnp]

You're assuming another rule here, which not only isn't written but is even explicitly excluded in the very beginning of this experiment.

[anilakar]

Both "No vehicles" and "in the park" already require you to have external knowledge. What is a vehicle? What constitutes park grounds?

[vidarh]

That is part of the point of the exercise. You can expand on this rule, but however far you go there will continue to be things that are not clear.

[raverbashing]

Correct. But you (and the experimenter) are assuming that rules exist in a vacuum, which in practice it isn't

[jodrellblank]

No the experimenter doesn't assume that, they say: "please answer the question of whether the rule is violated (not whether the violation should be allowed)."

The intent of the experiment is to get your view on whether X is a vehicle or not, and whether Y counts as a place "in the park" or not.

[watwut]

Yes, but that is an actual situation in real world.