That's actually reasonable, I think

I don't think police are going to be driving around trying to find loose chickens so they can fine their owners. I think it'll probably be a case of if your chickens are on someone else's property, and they don't want them there, then they will call and report it. Hopefully they talk to you first, but if they do and you don't take steps to fix the issue, then it's definitely reasonable.
I love my birds, but I can totally see someone not wanting chicken poop all over their yard, or their gardens trashed and their hard work eaten, or their landscaping torn up by scratching chickens, etc. You could still free range, so long as your birds stay on your property, or your neighbors give you permission and don't mind the birds wandering onto their property. It's only an issue if your neighbor has asked you to keep your birds off their land and you don't want to respect that.
Unless it's going to be something like every chicken not in a run is an instant fine. That would be ridiculous if your birds are on your own property.
Sorry, off-topic I know.