UniChris

The reality is that you will rarely find a traffic court administrative judge that interested in hair splitting.

The other reality is that even having to deal with the system is more than half of the punishment, valid ticket or not.

That can lead to things like someone's recently shared case of getting a ticket for running a red, and also for not wearing a helmet (which is not a violation for an adult recreational cyclist here), and deciding to pay both because they actually ran the red, contesting the cop's disregard of the text of the helmet law alone is not worth the effort since there would still be a valid red light violation to pay. (though yes, there is also the strategy of contesting valid tickets and hoping they don't show)

Nor again, is there anything stopping a city from writing ordinances banning specific behavior in parks when there is a legitimate government interest to do so.

Nor is not requiring equipment that would determine if a violation is occurring an impediment to making that a violation, you can for example close a park at a certain hour with signage, without requiring that someone wear a watch if they wish to enter. You can ticket for parking within 15 feet of a fire hydrant, without requiring that every vehicle have a tape measure in the glove box or that drivers be able to recite the dimensions of a sidewalk paving square from memory. Yes, many oft-violated technical regulations do get additional requirements for monitoring equipment to back them up - but that's to enhance compliance, it is not in any way a requirement for such a regulation to be valid.