I think you are right. I think agreement would be even higher if you would be asking people what should happen as a result of the situation as described. There could be options with increasing level of seriousness. Things like “do nothing”, “send a park officer to ask them to leave, they get a fine if they persist”, “send a cop who asks them to leave and arrest them if they perist”, “send a cop to arrest them without warning”, “order a snipper to headshot them without any warning”.

I think asking if something is a violation is too abstract, and people are bad at abstract things. On the other hand when we make it concrete people will be better at expressing what they think should happen and you are more likely to see agreement.